Ok thank you I'll be sure to post if that does or doesn't fix the problem

 

Ok pulled the jug inspected everything and it all checks out good. Did a compression test and still having issues pulling over. Now I am running 15.1 cause it's almost the exact same setup that's on the powermaxx I have just without the powermaxx build. I'm now leaning towards having a ignition issue possible timing of the total loss flywheel might be lighting the plug at the wrong time.

 

Maybe the after market ignition has something to do with it,but that doesn't explain away the 70 psi compression you mentioned earlier. Needs to be at least 100 psi for most to even try to crank,plus if the top end has been done right compression should be in the neighborhood of 145 psi or so.

 

I'd test your compression tester on a running machine...you mention 70PSI and it's hard to pull over...something doesn't sound right...
OPT is trying to confirm one piece of the equation...once confirmed he can help you diagnose the others...

 

ive gathered alittle more info on the motor I have from a person that had there hands in building it, its built almost to the same specs as my 416 powermaxx that I have and its just as hard to pull over as the build im messing with right now that's not a powermaxx. same piston size and everything and is built to put down around 90hp when it does decide to start and the powermaxx that is just as hard to start reads the same compression bein im tired as all hell from pulling cause its so high. other words I don't have the nuts to keep pulling it over to get the compression to read correctly. and the powermaxx runs like a champ. just takes alittle to start cause its such a high compression. that's why im leaning towards either I don't have enough voltage to get a good enough spark in the motor, or a timing issue for the ignition. and what brand gaskets would be good to use since I pulled the cylinder apart to inspect everything.

 

Oem,Cometic or Vesrah head and base gaskets are the only three brands I'd trust.Wouldn't trust none of the other crap gaskets on ebay or amazon. As far as what other problems you may have ,the only thing I could do is refer you to a service manual so you could go through the electronic trouble shooting guides along with the resistance tests.DOWNLOAD Polaris ATV Service Manuals By Model & Year

 

90hp...out of a single cylinder 400cc...wow!! I'm getting maybe 55-60 out of mine and it's ported in addition to all the normal goodies...


Anyway...if that thing is really laying down that kind of power it'll need a custom head gasket and I'm pretty sure the head needs to be girdled as well. I'm pretty sure the stock bolts wont hold on to that head for long...Ritter or Aaen are really the only players left...HPD's full-on race mod was pushing 75+, required a girdle kit and required race fuel (just as an example)...


Once back together, I'd get a hold of a stock ignition and see if that fires the beast up...tough to diagnose highly modified toys...

 

That and more so..

 

yea the powermaxx I have is one of Darrells custom built ones he did and its on race gas and runs a 4.6 300ft needs alittle more tuning and I have race gas on this one too if it will ever start im running a msd 4270 total loss system and has no oem harness msd wiring only. this is a strictly sand drag only. only thing electrical on it is the picups from the total loss flywheel set up, ignition, battery and coil that's it

 

OK...thanks for clarification...not even sure if a stock starter/battery could even turn over something like that...sorry can't be of more help but you are playing in a sandbox most dare not enter


I'd be super curious to see some pics...I'm guessing the jug/head are custom with hardened bolts if not girdled...


I could definitely see a challenge with the ignition...getting the timing right with non-factory items should be fun...