11:1 compression vm26mm carb, dont start

[Latent]

I have a fully built clone just replaced fuel pump because the other one had a leak. Used to start in a few pulls, pull started it right after its compression stroke and now it doesnt start at all, but has compression and spark. I pull start it right after its compression stroke to just right before the next one before the snap back... i have a genuine v26mm mikuni and the carb spits out gas randomly when i pull start it ( carb farts ). However i hear some denotation from the xhaust and carb from time to time as well. There was also some smoke coming from the carb some light smoke perhaps burnt gas... I have played with the air/fuel mixture from half a turn all the way out to 2.5 turns and can't seem to start it. Seems odd because it was running perfectly just before i replaced the fuel pump and cable to the mikuni. any help is greatly appreciated... :doah:

would an electric starter fix this problem?

 

[Txpowdercoater]

check valve adjustment, and check flywheel timing/sheered keyway if the valve adjustment is good.
no electric starter is not needed, I have a clone with higher compression than yours and it pull starts easily everytime.

 

[Latent]

what are recommended setting with champion roller rockers ?

 

[Latent]

at TDC the intake valve measured .020 and the exhaust valve measured about .013 :doah:

do you think this would cause the engine not to start? What are the valve adjustment for champion rockers is it .005"?

 

[shackwrrr]

Sounds like timing is off, check for sheared key.

 

[Latent]

re adjusted valves, would the cold weather 19 degrees play a role In my problem?

 

[ole4]

.030 and .015 iw way too loose. did the lash caps fall out? Should be .002 to .003 valve clearance. be careful at tds compression release can screw you up. (If your cam has one)

 

[Latent]

no lash caps are still on and what method do you use for setting lash? would the loose lash settings cause the motor not to start? why is my carb farting?

 

[rmm727]

needs to be at TDC on the compression stroke, not exhaust stroke when the compression release kicks in. you're loosing a lot of lift with the lash set that loose.

 

[Latent]

re set lash, but this motor went through 3 pullstarts in the last two weeks none of them have strong enough string for the compression :doah: are there any clone pullstarts with stronger string? might be worth it for a hand held starter

 

[Txpowdercoater]

re set lash, but this motor went through 3 pullstarts in the last two weeks none of them have strong enough string for the compression :doah: are there any clone pullstarts with stronger string? might be worth it for a hand held starter

real world terms.
gap is to big, and doesnt allow the exhaust compression release to work, henceforth the broken pull strings, sore fingers and not starting.
take your time, set the valves with a feeler gauge at ex.003 in .002 and go have fun. Make damn sure when the locknut is tightened, you dont change the adjustment.
If this is all gibberish, do a search on valve adjustment, maybe a utube vid to help ya....easy stuff, just take the time to do it right.

 

[Latent]

I reset both valves to .005 at tdc after intake valve closed. However won't be able to fire it up until either I get my hands on a pull start or an electric starter and kindve leaning towards the electric start. I already went through 3 pull starts -___- Is there such a thing as a heavy duty pull start for high compression motors? :laugh:

 

[Txpowdercoater]

I reset both valves to .005 at tdc after intake valve closed. However won't be able to fire it up until either I get my hands on a pull start or an electric starter and kindve leaning towards the electric start. I already went through 3 pull starts -___- Is there such a thing as a heavy duty pull start for high compression motors? :laugh:

set them closer to the specs mentioned,

again, if you have it correct, the exhaust cam lobe has a compression relief built in, if the gap is to large, it does'nt release the compression.....you dont need a special rope of space shuttle materials....I have approx. 13.1 comp, monster cam, runs on 112 race gas blah blah blah....starts with a stock pull rope no problems.

 

[Havasu Dave]

I'm no expert on these engines, but it started good with leaky pump, changed the pump, and now it doesn't. So I'd be looking at what I did when I changed the pump.

I know on my Tec, a backfire sheared the key- twice.

Is higher pressure fuel in a non-leaky pump, now overwhelming the needle seat in the float?

I just wonder why one would look at valves, or internals, when all that changed was a fuel pump installation.

 

[Txpowdercoater]

I'm no expert on these engines, but it started good with leaky pump, changed the pump, and now it doesn't. So I'd be looking at what I did when I changed the pump.

I know on my Tec, a backfire sheared the key- twice.

Is higher pressure fuel in a non-leaky pump, now overwhelming the needle seat in the float?

I just wonder why one would look at valves, or internals, when all that changed was a fuel pump installation.

we are looking at valve adjustment because he is stating he has them set waaaaaaay out of whack and it broke numerous pull ropes etc etc, that = valves out of adjustment or a compression release on a cam that isnt working properly.
There is more to the story than being told, but we have to go on what he is telling us, right or wrong, its all we have to diagnose with.

as well, I have mentioned he needs to check timing, Its hard to help someone when they dont follow the answers given. There is a few bits of data that is needed to properly diagnose, but again, we have what we have for info, I'm sure if the motor was sitting in front of me now, it would be running if its mechanically able to because I can diagnose and know where to look for issues presented.

 

[Havasu Dave]

we are looking at valve adjustment because he is stating he has them set waaaaaaay out of whack and it broke numerous pull ropes etc etc, that = valves out of adjustment or a compression release on a cam that isnt working properly.
There is more to the story than being told, but we have to go on what he is telling us, right or wrong, its all we have to diagnose with.

as well, I have mentioned he needs to check timing, Its hard to help someone when they dont follow the answers given. There is a few bits of data that is needed to properly diagnose, but again, we have what we have for info, I'm sure if the motor was sitting in front of me now, it would be running if its mechanically able to because I can diagnose and know where to look for issues presented.

I was just offering my two cents worth based on my troubleshooting accumen based on the KISS method. You're right though, it's impossible to t-shoot over the internet. Hell, you should see what I am going through just trying to jet a Mikuni on a flathead! Or for that matter, an old Tec 4.0! That one's been at a shop for three months now, so I guess I'm just as bad at fixing these things as a the people I'm trying to pay to do it.

 

[Latent]

^ haha, i'm going to take off the flywheel and see if my flywheel key is sheared, i got a stock key and also a 8 degree key. I think the problem is due to a timing issue. I know the engine is mechanically sound, but there was some nasty kickbacks

 

[george3]

Sounds like the key Is damaged from the backfire. Comp. release damaged possably. Check key first might solve the prob. Stainless valves, champion rockers, Lash caps needed?

 

[Latent]

I have ss valves, lash caps,55pound dual springs, I'm removing the flywheel ATM

 

[gasman]

This may be a silly question, but is your fuel pump the same as your last one and are the lines hooked up correctly? Your not sucking fuel out of the carb are you? maybe try bypassing the pump just to try to get it started. If fuel supply is OK definitely check the timing.