70 won't start

[tbone]

I have an original 1974 Trail 70 that ran prety good but had stripped spark plug hole. I carfeully installed a heli-coil (w/o removing the head). Cleaned out all debris w/ cotton Q-tips, prior and during the instalation of the heli-coil. I put in new NGK plug. Now it will not start. It does have good spark (I checked with boot on and plug against head and saw a good spark). I have good fuel as well. When I kickstart, it feels like the same compression as before but not sure. Is it possible the plug is not deep enough now? It seems to butt up against the head as it did before. Just a thought. Any ideas or help as to why it won't start is much appreciated!

 

[mtkawboy]

Could be a lot of things, is the helicoil the same length as the original spark plug hole or is it a lot longer shrouding the plug & spark? How long did the bike sit while all this was going on, you could have plugged jets from bad gas? Have you checked that you have gas getting to the carb by opening the drain? Did the old gas sit in the crab while all this was going on and agin how long was this? This is pretty tough to do online. Let us know the answers to what Ive asked and we will try to go from there

 

[clubford00]

With the plug seated, Good Spark, and fuel flow, It should start. The only other reason for no start at this point, is if the timing has changed for some reason. Keep us advised as to your findings. Dean

 

[tbone]

The helicoil seems to be 1 thread too long. Not really shrouding the plug, but maybe. The bike ran 2 weeks ago and I have not tried since. I installed the heli-coil yesterday (saturday). As an fyi -The plug was so loose it actually popped out still connected to the boot when I ran it 2 weeks ago. I put fresh gas and some stabilt (for the winter) about 3 weeks ago. I know gas is getting to the carb as I loosened the fuel lines at the petcock. Other than the loose sparkplug and me installing the heli-coil, it started within 5 kicks and ran pretty good.

 

[clubford00]

If you have access to a compression guage, i would check it. You might be getting blow by passed the plug. If so the heli coil isnt in properly. the plug might apear tight but blow by the plug will negate any compression. Just another 2 c to contemplate. Dean

 

[mtkawboy]

I dont know, sounds like it should run to me. Greasing the tap for the helicoil is a better way then Q-tips to get the shavings. Let the gas dry out in the cylinder and try some starting fluid. One thread while not good for preignition shouldnt keep it from starting. I dont see how the timing could change on it

 

[tbone]

haven't looked at it in 2 days

what's the best way to let the gas dry out? Is it possible a burr from the heli-coil install is keeping a valve from closing all the way? would this keep it from starting?

 

[mtkawboy]

Not if like you said it had the same compression as before you put the helicoil in. You can stick a lighted match in the plug hole but it should be evaporated by now Id think. Try a squirt of starting fluid