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About procycles

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    motorcycle racing Flat Track and Ice Racing

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  1. Throwing my hat in to the ring. I would list all the "stuff" but I'm embarrassed by what I've spent on it!
  2. William, at no time was I suggesting he “jet away” his problem. What I WAS doing is explaining what causes the CONDITION so that he could understand more clearly how to solve the problem. That is something that no one else has offered. Whether you are interested in believing what I’ve written is your prerogative but you can be sure that when engines “back fire” it’s because there is combustion in the exhaust system. That is not a normal condition. The number one reason for this is due to overly lean idle circuit air fuel ratios. That does not mean that it’s the only possibility. Sure, there are others but when you are offering a layman technical advice it is far more reasonable to suggest what is LIKELY the cause and not all the obscure possibilities. The only thing that accomplishes is to add to the confusion and frustration on behalf of the reader. The best way to get to the root of any problem is to use a systematic approach and that comes only with an understanding of the “system” you are diagnosing. That particular model, DRZ400, comes from the factory with a very lean idle circuit. Increasing the pilot jet by one step on a stock model will produce no negative effect and, in fact, will increase overall drivability. Change something around in the intake or exhaust and it will easily accommodate the next step up in the pilot. That’s just that bike. Others, not necessarily true. Two steps up on the pilot from stock, on that model; with the modifications listed in the beginning of the post are well within the ideal idle air fuel ratio parameters. I’m sorry you don’t agree with that and are suggesting that I’m offering the incorrect solution. And I do agree with you that there is often many ways to do something wrong and usually only one way to do it correctly. However, what I’ve done is explained clearly and concisely what causes this problem and that is useful to anyone who takes the time to read it. If I were to pick a hundred bikes that experience popping on decel that I’ve seen in my career, I would say that 95 of them were due to overly lean, idle air fuel ratios and the other 5 were from either bad exhaust gaskets or cracked header pipes. These are statistics that should not be ignored. They are well documented and understood by most all professionals and high profile technicians in the industry. My response was professional, non-condescending and educational. I feel confident that most would agree but that is certainly open for debate. Just sayin…….
  3. Well here goes....... You need to put a larger pilot jet in that carburetor to ELIMINATE the backfiring on decel. This has to be one of the most mis-understood phenomenons in this business. "jet kits" do not come with pilot jets. Although they should in many cases, especially a DRZ400. The needle or the main jet has nothing to do with the Air/Fuel ratio in the closed throttle position. When the throttle is closed the only fuel the engine gets is via the Idle Port. The Idle port is located in front of the throttle blade closest to the intake manifold. The only time there is enough "signal" (engine vacuum) to pull fuel from this Idle Port is when the throttle is closed such as on decel or at idle. The fuel the engine gets via the Idle Port flows through a restriction called the Pilot Jet. The size of this Pilot Jet determines, to a large degree, the Air/Fuel ratio at idle. The mixture screw provides a final coarse adjustment at the Idle Port in determining how MUCH of the MIXTURE is delivered to the Idle Port and then on to the engine. This can sometimes overcome the problem but often it's just does not have enough impact on the Air/Fuel ratio to make any large difference. However, when you are coming down suddenly from a high rpm by closing the throttle completely the only fuel the engine gets is through this Idle Port which is designed primarily for idle conditions. In most circumstances and in stock form the Pilot Jet is large enough to supply the correct Air/Fuel ratio so that the engine idles smoothly and does not create a lot of HC and CO. When you begin changing things around such as removing baffles, changing exhaust and or changing air filters you create a lot more air flow through the engine and the stock Pilot Jet is too small to maintain a reasonable Air/Fuel ratio. When this happens the Air/Fuel ratio at closed throttle is too LEAN for the conditions and this causes the mixture introduced in to the combustion chamber to not burn completely or not at all. This unburned mixture (raw fuel or HC) is then sent in to the exhaust system where after several combustion cycles eventually becomes combustible and suddenly explodes. You will notice there is a rhythm to this popping sound and that's because it takes the same number of cycles (frequency) to get the unburned fuel in to a volatility window where it can ignite. The way to correct this is to richen the Pilot Jet. That's it. Not sure about this? Pull your choke knob out the next time this happens and see what happens. Noise disappears. That particular model of bike is on the lean side to begin with. The Pilot Jet is marginal at best and any modifications that allows more air flow just puts it over the top; too lean. It's a good carburetor for what the design intent of the bike is. They are smooth, deliver good gas mileage and won't stall or hic-cup. That is the advantages of a Constant Velocity (CV) carburetor and that also explains why they are so prevalent on street bikes. That bike is street legal and thus the CV carb. I've dynoed plently of them and you can really wake them up with some simple mods which do not affect reliability and make them a little more fun to ride. Just sold my 08 DRZ400SM. It was a blast to ride around town. Kind of miss it already.
  4. My first advice to you would be to not return to that shop. That is just ridiculous. When you set valve clearances you don't set them according to the type of riding you are doing. Nothing in the Honda factory service manual states setting ANYTHING on that engine according to whether or not you are "racing". It's assumed you are as it's a "Race bike"! Frankly, it's just a matter of ignorance on behalf of the person who told you that. You set the valves on ANY engine according to what the manufacturer specifies or what a competent race engine builder requires for a special high-performance engine. On a stock bike the valves are set to what the factory service manual calls for. It's that simple. There are no other factors involved in that decision making process. Can you imagine if there were? How confusing would that be? When you set the valves on the loose side of the parameter you will have later valve timing, not less hp. Dang it all that is just nuts!! Valve timing is critical when you are trying to achieve something very specific. Not GENERAL maintenance. Problem is ladies and gentlemen, there is a very enormous lack of training in this field and it's at a crisis level. The automobile industry went through this years ago and is much better than it ever was but still not there yet. Everybody wants to sound like an expert but does not want to dedicate themselves nor has the discipline to get to that level. There is a LOT to know to become confident as well as proficient in this industry and, unfortunately, most don't know what they don't know.
  5. My bad dude!! I should have looked at where you lived and realized you were using the metric system and converting!! For the life of me I can't understand why we in the U.S.A. are still using the antiquated SAE system. We should all be on the metric system as it is a far superior system for just about anything I can think of. Much easier to teach to new students too! Not so darn confusing and ambiguous!
  6. No, it does not make sense. First of all, if either of the intake valves were at .001" then it's likely that particular valve is about done. And it's also likely it's mate is done as well. When you check valves and the clearances are that small it's an indicator of them being at the end of their useful life span. They should have explained this to you and suggested replacing them. I know it's a lot more expensive than just adjusting them but you will be replacing them sooner than later anyway. It's a waste of a customer's money to adjust worn intake valves. It won't last very long at all and you can not "BUY" longevity by setting them at the larger end of the parameter. When the intake valves are smoked that won't buy you much more than about 30 minutes. That is just not a good practice. Unfortunately many folks, including lots of shops, do not have an intimate understanding of these engines and often offer bad advice. Fact is you will more than likely experience difficult starting sooner than later as the worn intake valves just pound further in to the head and wind up right back where you started and eventually they will have no clearance and then the bike will be very difficult to start or not start at all without push starting it. So in the long run you are spending more money, not less as you now have the cost of a valve adjustment and you will have to add that to the eventual valve replacement. This is not cut in stone but I've done dozens upon dozens of these engines and that's just the way it is unfortunately. And, yes, changing the oil often and keeping the air filter and housing clean and sealed properly is key in extending all aspects of the engine's life not just the valves. Engines DO NOT like dirt. Think of it like sandpaper. You don't want the action of sandpaper acting on any surface in an engine. Just not good. That's also why good engine assembly and top shelf engine builders have strict work habits regarding cleanliness. It's the single most important component to successful builds. By the way I'm not sure what racing or not racing has to do with anything. That engine does not know it's in a race against other bikes. If you are riding the bike on an MX track how is that any different than if you went there and entered a race? The rider is the rider regardless of any other circumstances. It's a "race bike" and it's intended use is for "closed course competition". Says so right there in your owners manual (that no one reads!) If you told me you were racing flat track with yours and not MX for example I could understand offering different advice due to the extended high rpm of flat track. Or if you were doing lots of woods riding. But an MX track is an MX track regardless of whether or not it's a race. That's just downright confounding albeit not surprising........ If you decide to replace the valves PM me or call my shop and I'll give you suggestions on what to do to eliminate this problem for good!
  7. Your spark plug is fouled now. Replace it and try it again. DO NOT change the starter jet unless someone changed it from stock. I agree with you putting all the settings back to stock. That's the right thing to do. That way you will have a good reference point and from there you can then adjust it slightly to your conditions. Like I said; when it's cold out you have to be careful with your starting procedure or you will foul the plug easily. I ice race a 2007 CRF250R and sometimes it will only be 10 degrees or even colder. I'm very careful how I start it and I see lots of people trying desperately to get their bikes started. Some use propane torches to warm the exhaust and some just tow them with quads! But the guys who have them right and understand how fickle they can be in cold weather usually get them started fairly easy. Modern gasoline just doesn't vaporize like the good old stuff. Too many additives and "crap" like ethanol in the blend. Having any amount of alcohol in the gasoline will really add to the struggle of getting them to start cold. Alcohol is a bitch to atomize, especially when it's cold. If you've ever been around alcohol burning race cars you've seen them squirt gas in the carburetor just to get them started and this is on warm summer nights. If you can afford it buy some VP non-alcohol blend of gasoline, 93 octane. We (motorcycle racers/riders) do not need the ethanol in our fuel. It's there for automobiles to help reduce CO (carbon monoxide). The government in all their wisdom has mandated this in most areas of the country and we get the raw end of the deal. Not only that it wreaks havoc with small orifices such as those that are part of small engine carburetors. It's not a problem in automobiles because they are all fuel injected now for the most part and it has no negative affect on the F.I. system. Sooner than later even off road motorcycles will all be fuel injected and the problem will slowly disappear.
  8. This really depends on the type of riding you are doing or are planning to do. If "peak performance" is what you need because you are racing flat track or any type of sustained high rpm racing then the stock type Titanium valves are better. They weigh less and therefore have less inertia and that makes them respond quicker. They have less "seat pressure" due to their lighter springs and they don't beat the death out of the valve seats. They are more expensive than stainless and they will not last as long either. The face of the valve is coated with a special coating that when worn will cause the valve to fail quickly. On the other hand, if you are a woods rider or just a recreational rider who wants less maintenance and is willing to give up a tiny bit of performance then I would suggest stainless. They do, however, weigh significantly more than titanium and will require different springs which ads cost when installing for the first time. They can also be a little tougher on the stock valve seats due to their increased seat pressure. When ever I'm building a race engine I use Titanium. For the rec riders and many folks who are not so concerned with peak performance I use the stainless. The bike's I've installed stainless in never come back! That's not good for business but it makes for better customers.
  9. Putting a bigger main jet in won't do anything to help it start cold or hot. It has nothing to do with starting. In fact, you could take the main jet out, throw it over your shoulder and the bike would still start. Just wouldn't be able to open the throttle. That motorcycle will start in temperatures ranging anywhere from 100+ to below zero without changing anything on the carburetor. You will of course have to change your routine/technique but you don't have to change anything in the carburetor. If it won't start in a couple/few kicks something is wrong with it. If the engine started when you got it back from the shop I doubt the valves have changed in 5 minutes. The valves do not need re-shimming. If you need to re-shim valves you really need NEW valves. New valves, installed correctly, will not need to be re-shimmed. Depending on what type of valves you use, stainless or Titanium, you can ride for a long time before ever needing to touch the valve shims. Stainless will last years. Titanium do have a limited life span but when the clearances change suddenly it's time to replace them.
  10. Wow! I can't believe you are getting clearance measurements to four significant digits. .0035" That's three and a half thousands of an inch. I'm not sure you can get that fine of a measurement with any conventional tools. I would say it's more likely your intake clearances are really .004" which is within factory spec. They should stay that way for quite some time neglecting any dirt entering the engine. It's been my experience when I've checked new or near new engines that the valve clearances are always on the tighter side of the clearance parameter.
  11. They were a great bike in their day!! I once raced a 1982 XR200R in a 100 mile national enduro down in Georgia. It had rained for a week prior and it was the nastiest thing I'd ever seen. That Honda XR200 never missed a beat the entire day and I was one of the only finishers in my class (200cc). They were considered a top level enduro bike for the B can C classes and many A guys used them too. It was before the days of expensive KTMs that currently rule the off road crowd. To this day I would still be happy to ride one in a tight woods setting. They are a cat in the rough stuff.
  12. Make sure the hot start piston is FULLY SEATED in the carburetor. If it's not you will have a helluva time getting it started when cold. Check your hot start lever and be sure there is PLENTY of free play in the cable, that the lever is not hitting something when returning to the default position and be sure the cable is smooth and not sticky at all. This is the number one reason for no starts I see on bikes equipped with FCR carbs and remote hot starts. Motion Pro makes a replacement cable for around $20.00 that works well. Use only Motion Pro cable lubricant and make sure the hot start cable routing is correct and the cable is not pinched anywhere. Set your mixture screw to about 1-3/4 turns out and be sure your idle speed screw is not set too high. (should idle around 1700 rpm when hot) Don't pump the throttle a bunch of times before starting. Pull out the cold start enrichment valve (AKA choke) pump the throttle no more than one time and only if it's COLD outside, not 70 degrees. Do not open the throttle. If you do you will diminish the effectiveness of the cold start enrichment circuit. It should start within 2-3 kicks. These bikes will flood easily if you start pumping the throttle and then it's a beeootch to get them started. If everything on the bike is where it should be they will start like this every time. Put the Boyseen Quick Shot on ebay and buy a new rear tire with the money you get from the sale. (the new rear tire will provide you with more performance enhancement) That part is completely unnecessary. That carburetor will work perfect without any aftermarket parts if set up properly by a competent technician.
  13. Try this: Loosen the throttle housing bolts, slide the throttle assembly to the right slightly and re-tighten. Also, try rotating the assembly either forward or backward slightly after sliding it to the right. This usually fixes that problem 9 times out of 10. The plastic throttle pipe can also get warped and will stick in different spots on the bar. Just loosen the bolts and try moving it around until you get the results you want.
  14. No doubt the front brake on the CRF150R is weak. I've heard this complaint more than once from customers. It is a fairly outdated system that was used on the CR80 back in the 90s and never updated (for some unknown reason). Here is an inexpensive alternative to the other stuff mentioned above, which by the way, will work well also. The problem with the current brake system is the caliper. The piston area is too small to generate the "force" (with the pressure from the supplied master cylinder) that is necessary to squeeze the caliper enough to get it slowed down as we would like it. You can install a different Master Cylinder with a smaller piston. Doing that will generate much more pressure and create much more force at the caliper piston. Typically, the systems with dual piston calipers (more area) will have a master cylinder with a smaller piston. If you simply install this type master cylinder on your current system you will increase braking force. Any of the bikes that come with dual piston calipers will have smaller master cylinder pistons. Bikes such as KX85/100 would be a good choice. Should be able to buy one of these on ebay for cheap. Nothing else will need to be changed. Installing a good braided steel line will only help eliminate loss of pressure in the line so that's a good upgrade. Also, install OEM brake pads. They are hard to beat for stopping power. Other companies offer good brake pads but usually give up some other quality to increase something that you probably don't need. Unless you are road racing the bike you don't need any thing other than OEM pads. Brake systems are simple hydraulic systems that behave by these laws: Force = Pressure x Area so then Pressure = Force/Area and Area = Force/Pressure. You can manipulate these any way you want to achieve what you need. Increase the pressure you will increase the force and that will get you stopped quicker. Easiest way to do this is by installing a master cylinder with a smaller piston. However, the inherent design of this front brake system may just be too inadequate even with modifications to satisfy a full grown adult at high speeds. But I think for appropriate youth riders you can get satisfactory results with this system and this simple mod. Funniest thing about it is that the CRF150F (trail, play bike) has a much better caliper than the 150R. I wonder who was on the committee that made that decision? This is one instance where the accountants over ruled the engineers.
  15. The kickstarter return spring can not "come off" so long as the RH cover is attached. The RH cover has a "boss" that keeps the return spring located in it's home. When you removed the RH cover to investigate you probably, unknowingly, caused the return spring to pop out of it's home. This happens all the time and if you are not aware of this situation it could cause you to start wondering! If that engine stopped dead while you were riding it there is something else going on. Of course if someone has been in your engine I would start there first as they could have done something wrong to cause this problem. If it has never been apart since new then you have something going on that needs to be investigated. It is not "normal" for any engine to just lock up while running. I hate to say this but it sounds like it heat siezed. By the time you got it apart the piston had cooled enough to begin moving again, thus fooling you in to thinking that it was the kick starter spring. Don't be offended as we've all been fooled by stuff like this. You can't learn much if you never attempt anything. Again, you need to find out why it locked up. First check your cooling system to ensure the coolant is full and hadn't leaked out while riding. Run that engine without coolant for even a little while and it will seize up. Also check your oil level on both sides, engine and transmission. Remove the large round plug with the hex on the transmission side and see if the oil level is just below the opening. The engine side needs to have the oil full or nearly full all the time. Of course anything is possible but I would lean this way if it were in front of me. Good luck! I