helpin out a friend with his apex

[rd2005]

Im trying to help out a friend he has an 90 apex 2010 and he put a malossi head on about 2 months ago and he is replacing the pistion what comp should it have the motor is still a stocker and he is running a slipper sprocket. The comp test he is getting about 83 psi. My apex s are way diffrent than his so Im not sure my self, any help would great

83 is very low... On our built motors we run between 160 and 200, depends on the head.... If he has replaced the piston and gaskets it should be around 160 stock.....

[rd2005]

Thanks for reply. Ok so now we know that's to low. I wondered if he should be using a comp gauge made for bikes or the regular automotive gauge will work fine. Also what would cause the comp to drop after what he did? Thanks

I use the same gauge as I do on all my big rigs. It normaly takes 8 to 12 kicks for it to build max psi. If it is all seal up good and still has low comp. Then most likley is the rings are bad or cylinder is scared or could also have bad seals but not likely. Most Malossi heads are hi-comp so that should be building compression not making it worse, unless the head is bad. Pm me more info and I will help make that thing fly!!!!

[rd2005]

Hey thanks. When I get off work I will go over there and give ya a shout. Going to pm you to. Thanks

Pm sent!! Look foward to hearing from you!!

[mmsoup]

Not trying to be disagreeable

I have three Malossi Big Bores and work on a fourth. I have built more than 10 of these and have ranged the squish between 25 and 32 thousandths and they have all ranged between 145 an 150 psi.

That's what you should see unless you run the squish down real tight which won't be sustainable


M

[rd2005]

Thanks for the input mmsoup. I had him get a suitable gauge & were getting 150. Quad is running smooth & responds quickly on the throttle. Couldn't test it fully due to weather but he seems happy with it as do I.