Vmax-4 Compression/price

[Vmaxkid]

Any idea what compression should be on the cylinders for a 1993 Vmax 4? I'm being told that the motor is freshly ringed and has the following 98, 99, 100, 100. I was also told that this motor is run at an elevation of 3400 feet and it is ported, polished and fires at 180 degrees. What do you guys think? Also, what do you think it is worth?

[Master of Faster]

Sounds alright, stock engine at sea level should be 120-125. Higher altitude and aggressive porting will lower your compression. If it were me I would get the heads shaved to bring the compression back up. I don't know what it would be worth, maybe 5-600? "Professional" porting is expensive to have done, I paid $450 this spring to have a twin done, but that motor sounds like it still needs a couple things to be top notch, IMO.

What do you want to do with it? 180 degree motors are mainly just for very high rpm racing use.

[Vmaxkid]

I really only want the Aaen pipes this guy has but he wants to sell the entire package so I was thinking I could take the pipes which have EGTs on them and sell the motor off.
I have a big bore Hauck 880 motor that I am dropping into a 1992 Vmax 4. Some friends and I have pooled some money and bought the big bore and want to add some pipes, bored carbs etc and want to see what we can get it to do across the lake this year.

[Master of Faster]

That's a cool project, hope it works out well for you.

It hard to judge the price on a motor like that. Sometime modded motors are difficult to sell without knowing EXACT specs of what was done.

[Vmaxkid]

Anyone else have input on compression for this motor?

[AL P]

what kind of compression testor are you using? sometimes the long hose type will give you a low reading. not saying thats low for your altitude, i would`nt know about that, but just thought I`d mention it. and also, has it been ran since the rings were replaced? did you do the test dry, or wet? or both? AL P

[SRV540]

how much are they usually off AL? As I have a cheap compression tester from Canadian Tire that has a 12" hose on it. are the short ones more acurate?

[AL P]

Last year when I rebuilt mine, i was worried about my compression which was reading low, and was told here on this site that the cheap hose type testors can "sometimes" read as much as 10 to 15lbs low, the main reason for this would be because the hose will expand, absorbing some of the preasure. this would`nt be a problem if the shrader valve was located on the threaded part that threads into your cylinder because the hose would only expand so much, before it stoped. the shrader valve would prevent the hose from shrinking back down, by not letting the air "back up". but unfortunantly, most of the cheap hose type gauges not only have soft hoses, but they also have the shrader valve located at the far end of the hose near the gauge. considering the small volume of air comming out of a two stroke, it does`nt take but a slight exspansion of the hose to give a low reading. another odd thing about the hose type gauges, is that they often read correctly on large four stroke motors. I believe they work good on larger four stroke motors, only because the sheer volume of the air. they put out enough air that the hose will expand as far as its going to, and there`s still enough air to get a good reading. the piece of crap hose type compression testor i have, proved this theory to me. it will only read about 70lbs on ALL of my sleds. vmax 4, 80 centurion, 79 TX-L, 72 arctic cat, ect. BUT, when testing my four stroke motorcycle, it read the same as a friend of mine`s snap on. 110lbs, on another motorcycle 115lbs. both gauges read the exact same thing. wierd aint it? ohh, the snomobiles all read good with the snap on! (normal range for two strokes):D sorry for the long post. just wanted to explain all my theory`s:D AL P

[SRV540]

thats a great explaination AL, thank you very much for that.......now I gotta get myself a better comp gauge. Mabey I will keep this cheap one for an RX1 if I ever decide to do the 4stroke thingy!!! So are snap-on gauges expensive?

[AL P]

i would check with a friend and see who has a known good one for sure, and compare them first, you never know, yours might be working right, I would`nt want to talk you into spending alot of money on one, just to find out it reads the same as the one you have. I was just saying what I`ve experianced, and also heard from others about the inexpensive hose type testors. I`ll tell ya though, i really wish i had bought a good one to start out with. when I first got mine, I seen it and thought, dang, look at this nice hard case having, chrome adapters, shiny black hose, pretty gauge, looking testor, and thought, its got to work as good or better than my bro`s testor that looks like it fell out of the back of a truck at 60mph, but when I first tried it, I got real low readings, and was totaly bummed thinking something was wrong with my rings, then i once again borrowed my friends beat up old snap on, and bingo, I had great compression. what really sucks, is that I lost the dang reciept. so now I`m stick with the prettiest compression testor around, that flat dont work for crap. ohh well, live and learn I geuss. actually I have`nt completly given up on it, I`m hoping i can find an adapter that I can thread into the cylinder that has the shrader valve in it, then I can just plug my hose into it, and see if maybe that works? I just hate to throw such a pretty tool away:D AL P

[toydoc]

With my Snap-on gauge.
93 was 130-140 stock 500mi
94 was 130-140 stock 1500mi, recheck after 5000mi with PSI quads still 130-140.

[toydoc]

anything under 100 sounds weak to me.
Add some oil in the spark plug hole, pull it over a few times.
Recheck and see what you have. Also check your gauge on a sled you know runs strong and see what it has.