2002 Bombardier DS 650 No Start HELP PLEASE

[Brock Kincaid]

Ok so just picked up an 02 ds 650 and the guy said he couldn't get it to start. He had a shop put new shims in it and I had them checked and they were ok now things I've done is new plugs even though guy had just put new plugs in it.. got new carb 42mm just like the one that was on it.. bought new intake manifold because the one that was on it someone got way to tweaked out and ported the sh** out of it excuse my language but yeah so installed new intake manifold and it just won't start like its not getting enough fuel.  Timing seems to be right it does fire every now and again but just barely.. did a compression test today and it was at 90psi.. i know thats low but don't know where I'm losing compression.. valves we at .06 and .07 when checked im lost ive tried everything I know and can't figure it out

[Mech]

Had any luck with this ?

 

Ninety is low for one of those. It could be burnt valves or bad rings. The way to tell which it is, is to put a little oil down the spark plug hole, give it a quick spin to distribute the oil then do a compression test. Oil will seal the bad rings up quite a lot, but have bugger all effect if it's the valves. If it's the rings the compression should come up to perhaps 110 or more, if it's valves probably only 95.. It depends how bad the rings or valves are..  You could also look at the exhaust for sign of oil burning which would indicate the rings.

I suppose you have changed the fuel ? Stale fuel can make for no start by fouling the plugs even though they don't look fouled, they will even spark when they are out, but not once the compression comes on. And, once stale fuel has fouled the plugs, they seldom come right unfortunatly. You could try holding them over a butane flame and try to burn them clean which sometimes works, but often not.

If it's been sitting I'd do that and try to get it going, the compression might come better with a run.. perhaps.. by a little.. but it's not really sounding too hopeful. It's always a good idea though to try and give things a run before you strip them down so you can check the gears and crank for noises etc.. It would be a shame to rebuild the top end and then find the bottom end was shagged.. and since someone has been modifying the inlet, we'd have to suspect it's been thrashed..