i have a dinli 90 with a 54 mm big bore kit so i have been trying to toon it in and it wont go like it should. so i ran a comprestion check and it is at 120 so what should it be at i thought it should be more but i dont really not sure so could anybody help please it has the factore crank in it too thanks

 

on the dinli can i put factore dinli head back because it has been shaved would it bring up the compresition on it???? or will it work on the big bore kit ?????? thanks if somebody can help

 

I'm pretty sure that the stock head has more CC's than the aftermarket, even with a shaved stocker. Try replacing the aftermarket gasket with the stock, my after market was .020" and the stock was .012". I bumped mine from 125 to 160 by replacing the gasket and shaving the a/m head a little. Once you start getting over the 160 psi you'll be getting away with being able to use pump gas plus.

 

thanks for the info but i run mix 110 gas anyway so how far did u shave the head????? i just run drag in 200 feet so it wouldnt matter about the gas thanks

 

I shaved my head .023", but I'm not saying this will work for you, or that it won't.

First your running race gas, totally useless on a low compression or stock motor, might almost hinder performace as it has the ability to smilulate ignition/spark on low compression engines.

If you do shave the head don't do it to much, especially if you ever plan to stroke the engine. I would look at using the thinner stock gasket or maybe seeing if they have a thinner base gasket that goes under the jug or use Phelnolic (spelling) sealant, its a sealant that is very thin and allows for around .004" irregularities. BUt make sure clearance isn't an issue afterwards on the lower rotating assembly.

There is a lot into setting up an engine for proper compression ratio, compression pressure etc..... I was under the impression that the big bore kit I got (same as yours I believe (hypertune) was set up for either the stock or the stroker engines until I went out and compression checked mine and took some measuerments.

I'll give you a little input into it ( these are from my years of experience in hipo gas engines and 2/4 stroke diesels). Proper squish area is around .040-.050", optimum is .035". Now to get that with mine I need to take out .037" off my jug or the base gasket (base gasket is probably .005). If I do that I will have .040" squish, and I can't touch anything else, head gasket or the lip on the underside of the head. Well I took .031 off already from using the stock gasket and shaving the head and went from 125 psi to 160 psi, if I take another .037 off I am going to significantly raise the compression psi by probably double due to the increase in compression ratio to around 225psi (thats a swag). Now will the head and studs take it? I don't know. To lower it I'll have to port the dome in the head. Which has to be done properly (this is another topic).

My recommendation is to either get the big bore for stock stroke ( like I was recommended) or stroke it.

I'm leaving mine the way it ios because my boy has about outgrown it and its fast, If it wipes a set off rings again or psiton I'll stroke it if I have the time and cash.

Any inputs from anyone else?

 

I wouldn't say race fuel is useless. It can enhance performance, particularly if it's oxygenated.

 

thanks for the help i am takeing it to the machine shop tomaro and see what they can do i will give him the numbers u guys told me about and i will go from their thanks for the help i will tell u how it runs after this thanks all

 

i did shave the head today and now it is 210 psi is that 2 much or should i lower it down a little ???????

 

Too much IMO. What stroke is that cylinder ported for? If it's a 54mm it is probably not right altogether. It should run OK. I'd use 2 base gaskets to lower compression. Theres no need for 215 lbs.

 

Which gasket are you using? The stock or the one that came with the kit.

Like fast dad said, I would throw another gasket in there.