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Found 46 results

  1. My brother was rebuilding my top end for me on my 2002 yz250, and due to a failure on his torque wrench, he over tightened and snapped one of my studs . Now i only have 5 of 6 working bolts on the cylinder head. I have 2 questions. We are supposed to be leaving for a 5 day riding trip in a few days, so we don't have time to order a new one. A: can I achieve enough compression and avoid any disasters for one week without 1 of the 6? b: There is a pretty awesome machine shop by his house that may be able to make us one, but I can't locate the specs. Does anyone have the exact specs for a 2002 yz 250 cylinder head stud? Any and all help would be much appreciated.
  2. My kx100 won't start. It gives a little purr when I kick it like it wants to. Spark plug is good. I never took apart the bottom end so idk if that could be bad. But I changed the piston but don't ask why but I used an old ring on the piston and one new one. The cylinder has a gash in it kind of like it was grinded by the piston a bit but that may be a problem. It's an 08. I tested the compression and got 85, and then tested 75 so it's bad. Could one bad piston be the problem? The piston was torn up bad so I'm sure the ring was bad. It was sharp too. Could that solve it? Thanks
  3. I just rebuilt my kids 2013 YZ-125 that I had the cylinder professionally oversized by 2mm from Millenium Technologies last year. It made it a 134cc. I just rebuilt the motor for this season, I had MT-LLC re-plate the cylinder and match it to a new piston. I also had them deck the head for race gas only. My sqush is at .038. I plan on running race gas (sunoco 110 non oxygenated) at 32:1 with Redline (which is what I ran all last year). Here is where my concern begins. I did a compression test and it is right at 220psi. Will I be eating main bearings quickly? Will this motor hold up for a season with exceptional maintenance? Should I advance my timing about .002 to compensate for the high compression and reduce the pressure on the rod? I was told to simply double the base gasket and it will work. IF I do that, What will that do with the timing and jetting? Just a little out of my league with this much psi..... Please help with ideas. Thanks.
  4. I have a 2006 kx250f starts first kick when cold takes a few kicks when hot but i was out riding with my buddies and i let one of them ride my bike when he went to start it up he kicked it over and was telling me it has very low compression and that it should not be that low, is this normal or a problem im just looking for someone who knows what there talking abouts advice cause if its a problem i wanna fix it to give you an idea how much compression there is you can push down the kick starter with your hand but it still takes effort. pic for attention
  5. My 2016 wr250f already run 8000km (5000miles). If it climb a steep slope with low rpm, I will heard some knocking noise from the engine, I guess came from the valve. If I keep throttle few seconds, the engine will stall and cannot start. At this monent, the kick starter is easy to push with a single hand. So, I guess the valves are jammed. But few minutes later, it will become normal. This happenned twice in the last 3 rides. Any idea about this symptom?
  6. This has been an ongoing issue, as I am sure some of you are beginning to notice.. sorry for the somewhat repetitive posts in advance. My valves were out of spec, I was only getting 85-90 PSI of compression. I shimmed my valves to the correct clearance, and I got the compression up to 150 psi. Now after riding my bike for 15-20 minutes, it will start doing the same thing it did before - it will idle super low and eventually bog out. I had the idle adjustment turned up very high, when I gave it a little throttle the idle would kick up for a couple seconds, then it would settle back down to extremely low and bog out. To me this sounds like something with the idle air circ, or jetting. Could something with the valves cause this as well? Want to get a second opinion before I send the head in for the $500 rebuild and still have the same issue. Thank you all again!
  7. In the manual, it appears that the rebound is on the same side as the preload adjuster and the compression in on the side with the radiator fill port. Yet, on the forks, there is an engraved R on the left side ( same side as the radiator fill port) and a C/P on the side of the preload adjuster. As I read/look at the manual, its is backwards based on the engraved markings. So, what side adjusts what?
  8. '09 DRZ400SM I replaced the rings and head gasket, and she starts up and runs just fine. Checked the compression after it was warmed up (air filter removed, throttle pinned open) and got a reading of 90psi. Put a teaspoon of oil in the cylinder, compression barely went up to 95psi. I'm at altitude, so the stock 135psi as per the manual would be 115psi here (5280ft = 15% compression loss). So right now I'm at a loss of 20% compared to a new bike at this altitude. is 90-95psi acceptable at this altitude? I'm not sure what normal compression would be for a 11 year old bike with new rings. I know a leakdown test would be best but I don't own one and don't have the funds to buy one right now. Otherwise I would just pressurize it and listen for leaks.
  9. I have a drz400s with a +4mm stroker kit. I was running a 4 layer base gasket to lower the compression bit ended up blowing a head gasket anyway from not tightening down the head enough ( did the 34.5 from the factory manual saw on here it was supposed to be 43). Now when the head gasket blew the head warped slightly so I got it resurfaced. When I got it resurfaced the machinest said he had to take .07 inches off which seems like a lot to me. Now with a stroker and that reduction in clearance I'm worried about where the compression ratio is. Has anyone in a similar situation got any insight? Should I be alright with a 4 layer base gasket or am I sitting on a ticking time bomb. Thanks.
  10. Hey Guys, I finally updated my old 2012 rmz with a run out new 17. I managed 430 ish hours on the old girl with 3 rebuilds no real dramas. Problem is the new 17 is already giving me the shits that something is not right with it. The very first time I started it it smoked alot, I mean alot. Its my 5th brand new rmz and none have smoked like this. Then with the first oil change post run in there was alot of mater on both the oil filter and screen. Second oil change was after a xc race and trail ride both in the same weekend, 5 hours. That oil smelt like petrol. and it seemed noisy. Then this weekend I went to do the acerbis 4 hour, was going good too 3 hours in and the thing got real noisy I had to pull out sounds like its going to blow up. Thing is it goes like a cut cat. Anyone had issues from new?
  11. Hey guys, I bought a 1998 yz250 that needed a top end rebuild. When checking the bike out the top end was already off, piston still on the rod. It turns over freely. I pressed the kick lever down and the piston obviously goes up and down. Basically the bike was a $700 buy that needed a top end. no big deal. new excel rims and dunlop tires, had everything to rebuild the top end already, new renthal bars, grips, etc. plastics worn out but no big deal. well worth the $700 in my book. So here's where my problem lies, after putting the top end back together, i'm finding it super difficult to kick. before i put the head cap on, the piston moved up and down smoothly in the cylinder as i pushed down on the kick lever. as soon as i put the cap on and the spark plug in, it became almost impossible to kick. I stand on my dirt bike stand to give me leverage on the kick lever and put all 200lbs of myself on to the kicker and i've gotta give it a little bounce to get it to kick. When it does drop all i hear is the piston stop at the top of the cylinder like its got all the air compressed. I'll reset the kicker and drop down on it and it'll kinda drop or get hung up like the piston doesn't want to suck back down and when the piston finally gets low enough in the cylinder i can hear a thump of air out the carb. I tried kicking this thing for a half hour with the piston getting hung up because of the compression not wanting to let it go. At least thats what i think is going on. and when i get the piston to clear the intake, it finally releases the trapped air. As far as spark goes, i've got a ngk 8es or something like that. not sure off hand. I do know its not the R plug. spark was there, wasn't the strongest spark but not the weakest either. Any idea on what could be going on? I think my next step is to take the plug out and see how easy it'll kick with out the plug in it. Any ideas would be appreciated, thanks.
  12. My husqvarna tc 250 2011 start to loosing compression ..Yesterday i tried to start it 20 light kicks nothing .Later i came back tried 4 hard kicks to low compression and started normally.Bike runs fine its not smoking , no power loss nothing.Bike have around 50 moto hours after top end .Sometimes it have really big compression and after two kicks almost none.Maybe decompressor is stuck open or something i have no clue...Thanks for any advice
  13. Should you still have to use the decompression lever on the compression stroke if no spark plug is in the bike or should it turn very easy?
  14. Hello All, I bought a 1995 Honda XR 250L cheap from a guy down the street who was moving. The bike ran but not well. When I received the bike it did not run. I do not know a ton about these bikes or dirt bikes in general. I do how ever notice a couple of things on the bike. The carb was dirty and I attempted to clean it. I didn’t notice that the diaphragm thing inside the carb. was rusty and didn’t look to good. I do not however know what it does or if it should be replaced. I then notice that one of the throttle cables was missing. If you are looking at the handle bars it is the lower cable. I went to buy a replacement but I am unsure of whether it is cable A or b. Lastly I noticed that the decompression cable is broken off and missing from the bike. I would like to see if this bike is worth putting the money into. What should the compression be? How do I initially set up the carburetor? Will it start without the decompression cable or other throttle cable? Does anyone have a pdf of the manual or a YouTube channel to help? Thank you for the help guys!
  15. Hi guys! I'm wondering if any of you know for sure if the advertised compression ratio of CP Carrillo piston for our bike is achieved with the single layer base gasket (.010" thickness) or with the standard 3 layers base gasket (.030" thickness). I'm asking this because I noticed they offer the same piston (12.5 cr) for both LTZ and DRZ but with different gasket kit, and it seems odd to me since it's the same engine.
  16. I’m new here. im doing a build on my 86 cr250 and I was wanting to shave the head for more compression. I was thinking, would it work just to put the head on the cylinder without the gasket and keep shaving it till it touches the piston, and then put the gasket on? What are your thoughts?
  17. Just got my ssr today will it be easier to start as i break it in. today it turned over after 1 kick sometimes and 10 kicks other is it the carb i bought a vm 26 but was waiting for the bike to break in befor installation
  18. Hi, just joined, first post. I'm stumped! Quick history of my last week, leading me to a compression test with unexpected results: It's a 2000 DRZ400S with Mikuni carb and 11,500 miles of which I have no clue the maintenance history of. Bought it from a friend who said it ran fine for him, just needed a starter. Anyway, it never ran longer than 5-10 minutes after I cleaned the windings on the starter motor and got it going. I took apart the carb and cleaned it, back together, nothing. Checked the carb about 6 times (watched every video on the internet about it, I'm pretty confident it's correct). Has good spark and a new plug, drained the tank and added premium with a little treatment, brand new fuel line, the fuel tank is breathing fine, the stator has no open, new battery. Did a compression test: got about 40 PSI. According to the wonderful internet that's about 100 PSI below what I want. Checked the tester gauge for leaks, nothing. Seems extremely low for an engine that was running a week before... Also there are no strange noises when it turns over. But not even a pop trying to start, even with starter fluid. Another back story: when I first got it I changed the oil and was surprised how gassy it smelled. After only getting it running for short periods, changed the oil again (when I checked the valves for clearances and any sludge, all looked good up top) and after just a few running hours the new oil smelled again like fuel. Right now the carb is off and the exhaust is off, can't find any evidence of a piece of valve broken off or anything obvious. So does anyone have a similar experience? Maybe broken rings inside due to fuel leaking by? I've heard the vacuum petcocks are prone to failure so I swapped it just yesterday with a manual one. It's due to the shop on Monday for a pro to get it running/tuned, but if I need to order a rebuild kit there's no point in that, so I'll order the kit and do it myself. About me: I'm an marine engineer by trade so engines are no mystery to me, but it's my first time digging into a motorcycle. I wanted some second opinions before ordering a rebuild kit. I'm happy to post pics that might help or do any recommended tests. Thanks for any info anyone gives me! P.S. -You guys have helped a lot with the little tips and tricks I've found on this website, I should have joined earlier. Any other Mainers here?
  19. I am looking for advice, my yz250f 2009 has had a issue for awhile now were as I can turn the bike over with my had quite easily. I have yet to do a compression test but am confused, the bike altough low compression does start eventually. easy cold but sometimes first kick hot but other times I'm there got 10-15 minutes. when trying hot it wants to start were it is almost starting everytime but I feel it just needs more compression to start. I have put new spark plug in and jetted carb to where I think it is not longer the problem. no shavings in the oil filter, what should I do ? put new piston and rings in it???
  20. Hi, Anyone on the forum, or can be referred too, that is an experience engine builder with extensive experience on this DRZ motor? Someone that has built multiple motors and fully understands camshaft profiles? Calling Hot Cams is useless. I have yet to call Webb. I know they are are good. They have done cams for me in the past. I just have a bunch of questions on what I can get away with without head modifications. Using parts off an E or e3 model. I've been digging around and found some info. Can cams from an LTZ400Z be used? Whats the profile? Are the e3 model cams from the 400e a direct bolt in? Springs OK? Decompression still active. I have a bunch of questions. If anyone can help, Id certainly appreciate it. Thanks!
  21. I feel like ripping my hair out! I bought a 2005 cr125 years ago, brand new. From day one it was a fouled. Eventually I had it tuned kind of good. A couple of years ago someone stole my bike. Obviously I recovered it. My crank bearings were shot. So I split the cases and changed them and both seals. After assembling the bike it smoked and bogged like crazy. I thought I may have fudged up the right crank seal when I installed it...nope changed it and still smoked and bogged and fouled. It sat up for about a year and I just broke it out again. It doesn't smoke as bad. If I idle for about 10 seconds it'll blubber and shoot out smoke before fouling a plug. The strange part it that it rides pretty good on the pipe, but out of the blue with blubber and eventually die. Now After cleaning the spark plug and kicking it, it'll turn over for a sec and die. The spark looks weak so I check it with a new plug and it looks good (so I'm assuming it's not the ignition system) anyone else have this problem? I'm beginning to think this bike is a money pit...but on the same hand I feel like it's something small causing all of this. Oh and also it's dripping that black crap from the tailpipe and plugs are always wet. I went down a size on the pilot...didnt help.
  22. hi guys, i got an apollo 125cc which is brand new but was sitting for some time. first day i got it on and it shut off and didn't turn on again. i would kick start it, it would rev super high then shut off and would lose the compression for a little then same thing again. I then got a new Mikuni carb online and replaced it and now the bike wont start and the same thing is happening, i try to kick start it and it sounds like it wants to start but then loses compression again for a little bit. Please help.
  23. I have a chinese WildFire dirt bike 250 pro and i got the thing on new years day 2018 for $300 it ran but it wasnt healthy its a four stroke and just recently completely cleaned the carb and it runs but i have to physically pour gas down the cylinder to start it.. Its got electric start but it doesnt spark and only sparks when the bike is warmed up so the only way to start it is pour gas down the carb and kick it or use starter fluid in which i dont have nor do i want to use it.. I just need help right now i have a scheduled trail ride with my buddies in a few weeks so i really need this thing to start without pouring gas down the cylinder (i dont pour much at all) UPDATE: the intake tube from the carb to the engine was not screwed in all the way so i tightened the &%$#@! out of it and i kicked it and it started after 4 kicks (not too cold but its 35 degrees Fahrenheit out right now) thanks guys for the suggestions!!
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