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Found 35 results

  1. Augoose

    60 psi after rebuild

    All, Question regarding expected compression after rebuild. 2001 DRZ400e. The head was redone by fast heads and I installed a new piston and rings. The cylinder still showed honing marks and had no scratches or gouges, so I cleaned it up lightly with a scotch brite pad (at opposing angles) and hot soapy water and put it all back together. My only spark plug broke during re-assembly so it has not been run yet. The rings were installed dry per directions in the sticky - I did oil the skirt however. I turned it over a couple of times to check compression and I'm at 60 psi. Is that normal for a rebuild that hasn't been run yet? I'm hoping that is because the rings have not sealed up fully? Thanks
  2. Last year I rebuilt the top end on my 2001 KTM LC4, new piston, rings, honed cylinder, new cam, and cleaned the valves and head. Now whenever I go to kick it, it feels like there is one stroke that is very difficult to overcome. The electric start can't overcome this blocking point in the engine cycle. The only way to get passed it is to kick exceptionally hard or to get it to the point of this one stroke, push hard to get past it then use the electric start or kick it normally. If I try to kick it without the above steps sometimes half way through the kick it just stops and slams a lot of force on my ankle and knee. Other than this the bike runs great when it starts. I am a bit baffled as to why this is happening, my guess is that it's the compression stroke and that the larger rings and piston I put in increased the compression too much. I do not have a compression tester but before I go down that path I wanted to get some opinions. Looking forward to your insight
  3. Heres a strange problem for the community, I have a bike thats failing a compression test but passes a leak down with flying colors... 2012 KTM 250 SX-F Valves spot on, clearances spot on New cam chain Dirt Tricks cam chain tensioner HAS fuel HAS spark 4% leakdown on the leakdown test FAILS compression test horribly Thoughts?? I am flat out stumped...
  4. Parker4570

    kx250f 2006 kx250f low compression

    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 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
  6. Supermotofool

    Valve Question

    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. Brandon Swan


    From the album: Brandon Swan

  8. 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.
  9. 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.
  10. 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?
  11. I'm having problems with my 92 CR125. I've had the bike a few months now and it's been running great (within first month of having it transmission messed up, tore it apart, fixed trans and put all new bearings in entire bottom end, crank assembly felt good so re used it), not really too surprising because the previous owner obviously neglected the poor thing. Anyways, after the rebuild (all new bearings and seals along with a few new transmission components) the bike ran GREAT, TONS of power up top along with smooth power down low (125 so not neck snapping but it was properly smooth till it starts revving hard). Recently I started getting a bog down low when opening throttle quickly and diagnosed the cause being low compression (90 psi no matter how many kicks I give it, builds quickly to 90 but won't go higher, with throttle open/carb removed also. So I assumed it needed a new top end (same top end when I got it), so I put the wiseco kit in and unfortunately same psi readings, 90 psi, needless to say stuff went flying in the garage. Checked everything the manual said it could be like head/gasket, base gasket, reeds (replaced with brand new reeds), still 90 psi. Re-inspected cylinder bore and piston and they look flawless. I don't understand what else it could be, please help! Im still currently riding the bike every weekend with the low compression, runs amazing well but I can feel the low compression when doing slow wheelies, bike dies out. It doesn't sound like it has an air leak, idles perfect and fires right up too, we ride for hours straight on the weekends and it never even flinches, runs excellent besides the low end bog (due to low compression), thanks for any help guys. My manual did mention one last thing that could cause low compression and that's the crank seals, didn't know this could affect compression but the Honda CR125 factory manual says it can so I'm not sure what to do about that. Inspected left side crank seal (flywheel), zero wetness, I installed new crank seals 29 hours ago ( that's how many hours the engine has on it since I tore it apart).
  12. Hey guys, So I recently just went through the bike and replaced the exhaust cam on my 2002 yz250f with an autodecompression cam out of a 2004 model. I then shimmed the valves, cleaned the carb, and replaced the spark plug. Now it won't start regardless of whether or not I try to kick it or bump it. It seems like as I keep kicking it it goes through periods of extremely high compression where it is very hard to kick and then periods of low compression where it is a little easier to kick. Either way I can't get the bike to start. Any ideas?
  13. DefyConvention

    Second oil filter underneath shifter?

    Good day all, I am riding a new 2017 kx450f, the first four stroke i have ever owned. I am also new to actually setting up a bike for me (sag, clickers, air pressure in SFF Tac fork, etc.) I have been going through the owners manual, break in process, oil change vids on youtube etc. While on the genuine kawasaki parts site looking up part numbers, I noticed on the oil filter section that there is the regular oil filter on the right hand side of bike, and then another one on the left hand side under the shifter. The second one I have literally never changed, nor have i ever heard anyone ever mention it, or speak about changing it, and its part number is 49065A. http://www.genuinekawasakiparts.com/oemparts/a/kaw/57f5247e87a8660d6c7c9b66/oil-filter Are the engine oil, and tranny sump separated on this bike ie two different oils, one for engine, and one for tranny? Or is this just another filter entirely for the engine oil, and should it be changed frequently? Also, on the fork and shock clicker setting there is a sign that is similar to " S<--->H " for clicker adjustment. Can someone explain the basics of this? Compression=? Rebound=? Thanks!
  14. jcarpurso

    2001 YZ250 Rebuild?

    Anyone out there that rides 2 strokes... YZ250 compression test came out at 215. I've had the bike coming on 2 years without a rebuild.. purchased used for $1450, original owner claims new top end just prior to sale. Not really sure how many hours on the piston.... but it's not like I never ride... seems a long time on the current top end kit to still have strong compression.. any thoughts? Should I rebuild anyway? I used to race as a kid and I felt like I went through top ends on my YZ125 left and right back then.
  15. So I picked up a project bike recently (another 2007 CRF250R) an the screws on top of each fork which allow you to go "softer" or "harder" are just not there. I have never removed any of those screws and wouldn't know why the previous owner did. The forks are working but I want to replace these screws and I am having no luck at all finding just the screws. Any help would be appreciated. Thanks, Skin
  16. I just sealed up my exhaust today with silicon sealant. However, when I turn the engine over slowly and hit the compression stroke (mid part of the kickstart cycle) I hear a quick hiss noise. It sounds like air being released somewhere. Is this the carburetor pumping air into the motor or do I have an air leak somewhere? It's really confusing and worrying me. It only happens while the exhaust is plugged. P.S I can't hear it when the bike is running it only occurs at this point while turning the bike over.
  17. SkInM4n

    2004 CRF80F problem

    So my son was riding his 2004 CRF80F around yesterday and had a major mechanical failure. I am unsure of the issue so I am going to post it here before I start the tear-down tomorrow. He was riding around hauling balls, as usual, and he said he heard a metal "clank" noise from the engine. Being the 14 year old that he is he kept ripping it and a couple of minutes later went OTB. The bike starts and runs but wont shift at all and when I clutch in and push it the bike only rolls a couple of feet before the rear wheel locks up. I have never experienced anything like this so any assistance would be appreciated. Unless I can spot something externally during the initial stages or get some definitive answer on here I will begin the tear down tomorrow. I will keep the thread updated on my progress so maybe it will help someone in the future. Thanks in advance, Skin
  18. NEWguyERIC

    Help Getting on the Trails

    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!
  19. 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
  20. 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.
  21. 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?
  22. vince46

    New 2017 RMZ 450 issues

    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?
  23. Brandon Trumbla

    1998 YZ250 Hard to Kick, Wont Start

    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.
  24. 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.
  25. nate9521

    yz400 compression?

    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?