Blaster Runs Odd

CodyEStanford

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Sep 16, 2015
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I was wondering if someone on here could help me out. I just rebuilt the top end on my blaster after buying it in non-running condition and it seems to still run like crap. Everything is new other than the crank seals. The bike doesn't have much rev to it, and when I go to ride it there is hardly any top end power. Any ideas?
 
Crankseals leaking maybe,...
leak test it!
Check the jetting, check reeds etc.
Yeah, I need to leak test it, reeds are brand new... But on jetting I don't even know where to start. I have an FMF Fatty Gold, Bill's Pipes Silencer, Vitos Stroker Crank +3mm, 68mm Wiseco top end, Ported exhaust. The stroker crank makes me think the port timing might be an issue and I'm half tempted to just throw a factory stroke crank in it.
 
Stock carb? 300+ main jet at minimum maybe 330( i have not much experience with the stock carb.)
The stroker crank has to be compensated with a spacer on the base off the cylinder.
 
Stock carb? 300+ main jet at minimum maybe 330( i have not much experience with the stock carb.)
The stroker crank has to be compensated with a spacer on the base off the cylinder.
Yup, stock carb with a 260 main jet, 32.5 primary... T.O.R.S. Delete. I do have the spacer plate on it. Looks like I might just have to pull the motor out do a good leak down test and go from there. Thanks!
 
There is no reason to pull the motor to do a leakdown test. You should also do a compression test and check the squish clearance.
 
There is no reason to pull the motor to do a leakdown test. You should also do a compression test and check the squish clearance.
I'm almost thinking the exhaust opening was ported before the stroker crank and now the port timing is way off. How can you check if the opening is where it should be, and squish clearance?
 
stock carb with a 260 main jet

there ya go, a 260 main is not rich enuf for your mods, as stated above, buy 290-330 mains, start large and plug chop down to find the correct jet............
http://www.blasterforum.com/threads/how-to-plug-chop.53237/



I'm almost thinking the exhaust opening was ported before the stroker crank and now the port timing is way off. How can you check if the opening is where it should be, and squish clearance?

I think......the spacer plate should have moved all stock-ish ports to the correct height.
if it was ported for a + crank, no spacer plate can be used.
 
I bet when you go to at least a 300 main, it will run a lot better but like was said, start big and plug chop down.
 
I bet when you go to at least a 300 main, it will run a lot better but like was said, start big and plug chop down.
Ok, so I put a 330 in and worked my way down to a 290 where it ran best, but when I have it in gear it literally has no power and it won't rap out over idle. I am stumped as to why this thing will not run. I guess the only thing I haven't done was change the crank back to stock stroke in case the jug was ported for stock stroke. Any ideas?
 
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Compression test ? Air filter clean ? Check you carb float height ? Sounds like it's not getting enough gas or it's low on compression
Do you happen to know the float adjustment measurement? The top end is all brand new and has good compression... Float is really the only thing I haven't messed with a whole lot.
 
20-21.5 mm.

Did you confirm that jet with a plug chop?
No, I can't get it to run good enough to get out of first gear... Set the float and tried every jet from a 330-260 and it runs the same no matter what jet is in it. Compression is good, coil is sparking. I just don't understand. My buddy has one with no airbox lid, factory jetting and aftermarket pipe and it runs great, pulls the front wheels with just a slight throttle goose. Usually the way my luck is though.