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About hgtuner08

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  1. its a 426 carb, I just ordered a long knobbed fuel mixture screw not pro-x but something like that. I let the valves be, im relatively certain right now that its a 2000 426. As far as I know there isnt really a way to 100% positively identify the engine year based solely on the engine serial. I guess what you had said was true in that if it ain't broke. Right now just wanna get the bike rideable. Maybe worry about a tear down later, I have great compression so I dont think thats necessary. Just need to figure out the carb issues. Its just odd, because the bike will run great on choke but die when its off. Im assuming this is basically because the carb is still gummy even after the cleaning. Must be the pilot jet right? Anyways Im just going to rebuild it when the kit comes in and then see where that leaves me, gonna try changing over the idle speed screw over. Hopefully that works. Ill post when I figure it out
  2. so just to reiterate, knob has a finite amount of travel and will stop spinning at top and bottom? I'll just swap it over
  3. yea I bought a rebuild kit, thats what Im gonna do is rebuild it and let it soak. The fuel mixture screw has always been this way, I guess just replace it? I have a whole other carb on hand because I lost this carb in a move and several years later, found it. Is it ok to let the carb to sit in the cleaning solution with the choke and hot start knobs still on? I followed the tear down procedure in the shop manual but do I need to tear it down further? Im using chem-dip soak solution off amazon.
  4. ok, I got the timing in and I think that was the real issue with the bike. I had let the carb sit for a long time and it was gummed up. Pulled off the carb and cleaned it. I think there is still an issue with the jetting and for some reason the fuel mixture screw was just missing. I had another carb on hand and pulled the mixture screw off of that, found the stock setting but im a little confused on how to set the idle speed knob. Can the knob top/bottom out? I just keep turning and it keeps going. I think this is the last issue I need to deal with and the bike should be good to go. Even after the cleaning, I was having the issue that the bike would run 100% like normal under choke, sit at a good idle and not bog if you twist the throttle. But the second you take the bike off choke it would instantly die. Do I need to clean the carb again? Im gonna buy a soak cleaner, will the choke and hotstart knob be ok? Do I need to pull the idle knob off or can I just dunk the whole thing? All the help I've gotten so far is really appreciated. Thanks Dewey
  5. perfect, found the stamp and it is a 426. Is there any way to establish if this is the original engine? If so I need to go with the stainless steel valves right? Would it make a difference if I bought titanium valves? I mean Im assuming there would be because of valve spring rate or something. btw thanks for the super quick response
  6. A while back, I bought a dirt bike from somebody off of craigslist. The price was so low it seemed like a no brainer. Its turned out to be a much larger issue than I wanted it to be but Im still somewhat satisfied with the purchase. I bought the bike primarily to work on and learn the ins and outs of a bike. So far Ive been busy. The issue I'm facing now is that the previous owner said the bike was a yz426, I ran the vin using the yamaha decoder online and it came back as a yz400 built in 2000. It not the biggest deal in the world but I had a couple questions. I changed the cams to a hotcams auto decomp cam. Originally thinking it was a yz426, i bought the yz426 cams. If it does turn out to be a 426 are the cams the same? The second and larger issue Im facing is that I think while the frame is a 2000 yz400 I cant be sure the engine is a yz400, I was going to replace the valves because even after adjusting valves and checking timing a few times the bike still back fires a lot. I think one of the valves on the exhaust is slightly bent, or the fuel mixture is off. I was going to replace valves anyways so on to ordering valves. I know that 426 valves 01 up are titanium while 2000 99 98 are stainless steel. titanium valves won't work with an older head right? How can I verify that my bike engine is a 400 or 426 or whatever the case maybe. Basically how can I assure the valve I order is correct? The reason I doubt the 426 vs 400 is that the carb looks like a 426 carb with the hotstart etc. I have the engine serial number, is there some way to verify cc based on that? Or even verify that it is original? Is having a 426 carb on a 400 going to lead to some issues? I guess its all about the jetting in the end right?
  7. so the allen head bolt was missing. I got the bolt on by using a tiny wobble attachment an extension and a slim socket. Will search for a replacement, this makes a lot of sense as it was a pain in the ass to try to get on. I'm pretty sure I got the timing right if this is the case because the punch marks were very close to the top of the cylinder head and moving them one tooth one way or the other would have moved them above/below the cylinder head level. It is possible because I was doing this by myself that after I set the engine to TDC via the timing hole, it moved very slightly off. While I was putting the cam chain on. I also replaced the cam chain while the bike was apart so I feel confident it's not a matter of having too much slack in the cam chain. If the timing is possibly off I guess checking it isn't a huge deal. Just gotta remove the timing plug, engine support, and valve cover but is it probably a timing thing? It needs to be babied and feathered otherwise it will die. Before I put the bike away I had given somebody the carb to rebuild but they lost the whole carb so I had them give me the cash to buy a new carb and I ordered a carb from keihen-fcr.com recently and thats what got me to try to get the bike started. The carb should be pretty fresh right? It had sat for a week while i was working on the bike but is that enough time to get the jets gummed up? Also is there a proper procedure for getting the carb cables put in right? No matter how I adjust them they seem to make the throttle way too tight. I have them at the absolute loosest they will go and the still making the throttle stick at little. Thanks for all your help grayracer, I know these questions are pretty novice but I still appreciate you taking the time to answer them.
  8. Got the bike started, second kick, and runs pretty well!!! Im so thankful, this is my first engine rebuild. Using the manual and some videos, made it through without blowing up the engine! Thanks for chiming in all the time GrayRacer. I just had a few more issues to work out so that I can get the bike to 100%. It won't idle off choke. I know that 99% of the time its the carb that needs cleaning but could it be that I got the timing off? I lined up the punch marks with the cylinder head with the cams facing out. I've heard that there are supposed to be 13 links between the cams, but I counted 12 and the cam chain was really tight. I could barely fit the cam back into its spot. The bike doesn't backfire at all at high RPMs. I did intake and exhaust hot cams. Do hot cams make the bike backfire or give it a hard idle? I found that when taking the exhaust off that the previous owner had dropped the bike and one of the exhaust studs was missing and the header was really bent out of shape. When I replaced the stud and tried to bolt the header back in, I realized that to get the header on I couldn't bolt the exhaust all the way up. The muffler isn't even close to being able to fit back on. I was going to say bent valve or something but when I did the leak down test after using marvel mystery oil, I got 5-6% blowby. Thoughts?
  9. I've gotten the head off and now I have a few issues. One of the intake valve shims was stuck so, using some advice from another thread, i hit the shim on the side with a spring loaded punch. After hitting it 10-15 times, the valve shim came out. Now trying to put everything back together the same valve's bucket will not fit back in. In addition there is some scoring near the valve bore but farther up than what the bucket would rise. Should I just replace the valve bucket? How do I know which bucket to buy (yellow, black, blue?)
  10. another quick question, if I performed a leak down test with the cams out this would basically check to see if the valves leak when closed and how much air would be blowing by the cylinder right? I cant hurt anything by doing this right? I have the cam cover off and the cam chain tensioner out as well.s
  11. So i was advised that some top cylinder lubricant would be a good idea, I took some marvel mystery oil and poured it into the cylinder through the spark plug hole and I turned the engine over by hand a couple times and then poured some more oil into the cylinder and let it sit for a few days. Today I had the time to really take the bike apart and really dig into it. Took the exhaust off, took the carb off, took the valve cover off, took the timing plug out and the crank bolt cover off. I then let the oil drain out and came back to set the engine at true top dead center. I was looking at the timing mark through the hole and it was a bit confusing it looks like I----I I I also didn't see any timing marks on the cam chain so, I guessed it was the last mark based on the direction of the cam lobes. The were both pointed outwards and approximately the same angle. I set the engine to last tic mark and then did another leak down test. Leak down test was performed by: 1. removing spark plug 2. connecting leak down tester to 100 psi air source and zeroing meter. 3. connecting tester attachment to spark plug socket 4. Make sure motor is at TDC and holding the engine while plugging the tester to the quick connect with some help This time I heard some leaking from both the intake and exhaust port but the leak down gauge was reading like 5% blowby so I guess the compression is good. Next I took a feeler gauge and tried to measure valve clearance. Half the valves are out of clearance, so im waiting on the shim kit to come in the mail to replaces the valve shims. I guess at this point my question is, when I took the crank bolt cover off, all the oil leaked out of the crankcase. Should i just pour some more oil through the dip stick tube? How much? I know that you are supposed to check the oil level when the engine is warm so should i just give a guess as to how much oil? Is minor audible leaking through the intake and exhaust ports normal? The intake port sounded like it was gurgling. Im just curious if the harbor freight leak down tester that I have is just not reading correctly. Could bad valve clearance cause the engine not to start? Thanks, Haraj
  12. Hi, New to the forums so sorry if this is already posted somewhere. I have an 01 yz426 that has been sitting in a shed for a couple years. It wasn't winterized properly before being stored and now I'm trying to get it running right again. I pushed the bike into the garage and pulled the carb off and got it cleaned professionally, put the carb back on and tried to kick it over and knew it had lost a lot of compression because I could push through the entire stroke with out using the decomp lever. Pulled the plug to check for spark which was good and then used a compression tester to check pressure, only got 60 psi after kicking it about 10 times (pressure rose each kick). Checked with a leak down tester and it failed but odd thing is, I couldn't hear air hissing from anywhere. I didn't open the frame oil cap though. I've basically been watching videos and waiting for my shop manual to come in but the question is, what's next? Any and all help is really appreciated. Thanks