09-02-2007, 07:53 PM #1
Don't over-torque your spark plugs
Well after doing a million plug chops and endless tuning while chasing down a performance issue, I suppose I wore out my plug threads or just plain overtorqued them. Only seeing this issue on the MAG cylinder, but the ski otherwise runs great. Just a heads up though. I've got a few extra cylinder heads around here, so no biggie I'll grab one of them.
BTW, I did notice that the MAG and CEN cylinder heads have a number 1 on them, while the PTO has a 3. What do those numbers mean? You can barely see it between the two head bolts closest to the rear of the ski.
09-02-2007, 08:31 PM #2
Hmm well now I don't know if I can use one of the cylinder heads I have lying around. They are all off a 650 and have a number 4 and a small "w". Opinions?
09-02-2007, 08:42 PM #3
Unsure on Polaris, but on Kawi's you shouldn't, for example, run a 440 head on a 550; too much compression, and WAY too little squish around the edges. Measure the diameter of the domes, see if there's a difference.
I noticed the #'s cast into the heads, mine are mixed too. 2's and 3's as I recall. Not sure what they mean?
09-02-2007, 11:18 PM #4
- Join Date
- Jul 2006
- Hays, Kansas
I'd just put a heli coil in it and be done with it. Much easier than even changing the head.
09-03-2007, 12:07 AM #5
- Join Date
- Oct 2006
- Cleveland OH
No, don't use a 650 head. It's much smaller in diameter and compression would be raised along with incorrect squish as Delagem said. Ebay or look for someone parting one out. Not too keen on the helicoil, maybe in a pinch, but get another head.
09-03-2007, 09:19 AM #6
i have 750 heads here 25.00 + s&h.
try a new plug first. you may have just "squished" the plug gasket too much.
send me an email if i can help.
Users Browsing this Thread
There are currently 1 users browsing this thread. (0 members and 1 guests)
By fire in forum 2-Stroke PerformanceReplies: 51Last Post: 06-12-2016, 11:11 PM
By ramairformula74 in forum Yamaha Open DiscussionReplies: 4Last Post: 07-06-2014, 08:38 AM
By CaptainReza in forum Yamaha PWC Performance (4-stroke)Replies: 16Last Post: 03-28-2012, 10:54 PM
By akjose in forum Yamaha Open DiscussionReplies: 2Last Post: 02-04-2010, 11:14 PM
By gianni57 in forum Polaris How To & FAQsReplies: 8Last Post: 07-30-2007, 11:35 PM