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Completely baffled, running issue, can not figure this thing out...


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Ya we need Carl on this. 

Def not the carbs.  Compression is way to low but everyone has seen this with a cheaper comp tester before. I’d try another tester just to be double sure. If your still getting 100 compression I’m guessing your milled head is where the problem lies.

The bike runs like the tors brain is connected ....which I know you double checked. Hmmmmm

 

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1 hour ago, Canadianshee said:

Did you have your pod filters on when you made the video. Have read in a different post of filters with outerwear that were over oiled was a cause of not reving out under load. It's not much help other then something to check.

Sent from my LG-H831 using Tapatalk
 

Nah no filters at all for the moment just to try and diag the problem, but I have had that happen to a buddy

1 hour ago, Ayesully810 said:

carb sync def aint that culprit here lol that thing wont rev for shit, jmo.  I have no other tips for you but ill be spying on here to see what it might be.

Im sure sleeper will chime in at some point with some og knowledge

Sounds good I appreciate the input, ill get to the bottom of it one way or another 

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38 minutes ago, gusto said:

Ya we need Carl on this. 

Def not the carbs.  Compression is way to low but everyone has seen this with a cheaper comp tester before. I’d try another tester just to be double sure. If your still getting 100 compression I’m guessing your milled head is where the problem lies.

The bike runs like the tors brain is connected ....which I know you double checked. Hmmmmm

 

Yea man its the strangest thing, but Im thinking your right in something being up with that head.  Like I said ill check the reeds in the morning

I'm more of a lurker, but I take it Carl is the OG around here when it comes to these bikes?  The more input/thoughts the better :)

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31 minutes ago, ZillaFreak said:

When you did the compression test, did you do it correctly?

Hold throttle open, kick till needle stop? Also, did the compression have the valve at the tip or in the gauge? Did the tip thread in the same length as the spark plug?

Yes, actually the first time I did it cold I just had the reeds on it, no carbs, second time hot after that short run in the vid, full throttle kick until it stopped moving, around 20-30 kicks per test.  Tester has Schrader valve installed at tip, and fitting is the same length as spark plug

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So either you have a shit tester or the head is fucked.

 

Like said before, have you check to make sure your head it flat and true? Might be warped. Also, check to make sure all your head nuts are tight, if loose, head can lift. The final thing could be a fucked dome design. I would say start off easy, check tightness of bolts. If good, might need to drain coolant and pop head to see if HG is leaking.

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27 minutes ago, ZillaFreak said:

So either you have a shit tester or the head is fucked.

 

Like said before, have you check to make sure your head it flat and true? Might be warped. Also, check to make sure all your head nuts are tight, if loose, head can lift. The final thing could be a fucked dome design. I would say start off easy, check tightness of bolts. If good, might need to drain coolant and pop head to see if HG is leaking.

Its possible the gauge is bad, it is brand new and only been used two other times this summer, once on my YZ250 just to see where it was at (that was close to 240-250) and once on this same bike before I tore it down to see where my compression was at, which if I remember correctly was similar to what the hot reading was now.  Still shit happens and the gauge could be bad, but I'm leaning more towards something is actually wrong internally

When I first put the bike together, I had an issue with coolant leaking around the gasket/up out the studs.  I removed the head and all the studs from the jugs, and checked both with a straightedge and feeler gauges, and everything was good and true.  At the time I was thinking I just did not have the studs tightened down enough in the jug.  Also, the gasket I was given was a bit strange compared to some new extras I had laying around, the extras I had had a "squish" element to them, i.e. raised areas around the bolts/cylinder etc, the gasket I was given was a flat piece of metal.  So I re-assembled it with one of my extra gaskets, and this time as per recommendation on here, I torqued the head first, in stages, THEN I torqued the jug bases, and the leaks were gone.  After a few more heat cycles and trying to diag the problem at hand, I went a check the torque on the head, no issues there.

It should be noted tho, the first time around when it was leaking and after I heat cycled it one or two times just to help break it in, I rode it down to my mail box and back, and it was doing the same thing that its doing now with it acting rev-limited and what not.  So it would seem the new and old head gasket did not contribute to the problem.

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Just now, gusto said:

Did Kevin supply the gasket with his head mod? 

Yes he did

I just got off the phone with him actually.  Gave him the run down of everything I've done and see what he thought.  He agreed with me in pretty much exhausting everything via diag on the chassis, and that the problem likely lies internally.   Told me the next step I could do, is send him the motor with the carbs on it, he'll put it in his test chassis, and get it running right.  Shipping/return shipping and his labor rate would put me around 500 or so, I'm in AZ and he's in Cali so not too far. 

I forgot to ask, but I would assume if there is an issue with the porting/parts or something that he supplied, and they were installed right on my end, that he would cover the cost of repair, but either way, I feel that this would be the next best bet.  Maybe I missed a part of the cases in sealing them or something strange like that, either way, at least I would know he would get it running right.

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If you haven't pulled your motor yet I went through my build book to see what I ended up with for a squish reading since we used the same builder with almost same set up.
0.062 size solder
Squish at cylinder wall 0.53 and 0.55 towards spark plug both cylinders.
This won't help your current situ but some more info to compare.


Sent from my LG-H831 using Tapatalk

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4 hours ago, Ayesully810 said:

Keep at it, you will get it situated. me personally I wouldn't spend the 500 bucks to go through all that. But that's just me. that's just too much hassle for something you will eventually solve

I hear ya, and it's not something Im thrilled about, but honestly I'm at the point where I'm ok with having him take over, sucks to fork over that much, but at least I know it will be in good hands

Not sure yet tho, I'm still thinking on it

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