time to rebuild?

978alwaysbroken · 02-23-2012, 01:30 PM

Hello hardcoresledders, I have a 2008 IQ Shift with 6000 miles(hard miles), and I am inspecting the top end. One of my valves has made slight contact with the piston without damage to either, the valve stops in the cylinders are getting quite worn, as are the valves themselves, i have researched this and plan on shaving the valves back, and have ordered updated washers that go between the valve and bellows(i would like to think they are a little thicker to keep the valve off the piston?). the compression is 138psi in both. I am also wondering if any play(slop) in the wrist pins/bearings is tolerable, when i turn the primary from side to side there is some play before the pistons actually move. I have not taken the engine down but i went in with a scope and everything appears to be in good shape. My main question would be is it worth trying to get the rest of the season out of it, probably 500 more miles, or should i tear it down and rebuild?

Michiganstopcat · 02-23-2012, 02:12 PM

Run it you have plenty of time in the summer to rebuild no use in wasting good riding time!! Like they say it will go or blow either one is fun in its own way!

JP33 · 02-23-2012, 03:59 PM

With those comp numbers and finding nothing bad during your visual inspection, I would run it and deal with it in the off season. There's not much left anyway.

shagsmc · 02-24-2012, 04:35 PM

I am a little concerned about my 08 600 Switchback, 5000 miles with 200 engine hours. After reading this I'll probably tear into it this summer.

poo boy · 02-24-2012, 10:30 PM

Can you explain what the washers accomplish? The valve land still sits on the cylinder land.

fastsleddr · 02-25-2012, 07:58 AM

BIGGEST concern with the 600 HO carbed motor is--the oil pump drive gear on the crank. They like to wear out at about 6000 miles.( I've seen this many times as I've rebuilt many)
I would run it the rest of the season, than tear it ALL THE WAY DOWN. and inspect the crank gear!!

Poo---In my research and engine rebuilding I found a place that drills into the cylinder and installs a stainless steel exhaust valve stop. Can't remember who at this time.

The reason the exhaust valve scuffs the piston is the stop in the cylinder, and the stop on the valve get worn. You can remidy this by grinding some extra clearance on the exhaust valve.

978alwaysbroken · 02-25-2012, 09:15 AM

I will be grinding the valve and running it for the rest of this season. Thanks for the heads up fastsleddr, i have yet to hear that in all my research on my sled, I plan on taking it all the way down this summer, and my hope is that i can 660 her( so long as i can scrape up the $).

Pro R · 02-25-2012, 10:33 AM

Quote:

Originally Posted by fastsleddr

BIGGEST concern with the 600 HO carbed motor is--the oil pump drive gear on the crank. They like to wear out at about 6000 miles.( I've seen this many times as I've rebuilt many)
I would run it the rest of the season, than tear it ALL THE WAY DOWN. and inspect the crank gear!!

Poo---In my research and engine rebuilding I found a place that drills into the cylinder and installs a stainless steel exhaust valve stop. Can't remember who at this time.

The reason the exhaust valve scuffs the piston is the stop in the cylinder, and the stop on the valve get worn. You can remidy this by grinding some extra clearance on the exhaust valve.

kraven on here sent me this last year about a company that does something like you are talking about, here is what he sent me.

IF you're replacing pistons, you may want to talk to MILLENNIUM TECHNOLOGIES about replacing/adding NEW exhaust valve "stops" into your cylinders. Remember the issues with high mileage stops becoming worn and then allowing the exhaust valves to contact the pistons

fastsleddr · 02-25-2012, 11:09 AM

Quote:

Originally Posted by 978alwaysbroken

I will be grinding the valve and running it for the rest of this season. Thanks for the heads up fastsleddr, i have yet to hear that in all my research on my sled, I plan on taking it all the way down this summer, and my hope is that i can 660 her( so long as i can scrape up the $).

If your a gearhead like me skip the 660 and go 685--I've had both.
The 685 is worth the extra$$$$$
I'm hooked up with makin the 685 kits,AND, the 660's for that matter. Pm me for pricing.

IQPolarice · 02-25-2012, 03:22 PM

I have an '07 carb with 7500 miles on it. Do you think I should rebuild? I did have an issue at the beginning of the season with both exhaust valves missing about half. That was when we cleaned them from last season.

02-23-2012, 01:30 PM	#1 (permalink)
978alwaysbroken Newbie Join Date: Nov 2010 Posts: 7 Current Sled(s): 08 IQ shift 600 Favorite Riding Area: pittsburg 10-11 Mileage: 2500 Age: 33 Riding Since: 2005	time to rebuild? Hello hardcoresledders, I have a 2008 IQ Shift with 6000 miles(hard miles), and I am inspecting the top end. One of my valves has made slight contact with the piston without damage to either, the valve stops in the cylinders are getting quite worn, as are the valves themselves, i have researched this and plan on shaving the valves back, and have ordered updated washers that go between the valve and bellows(i would like to think they are a little thicker to keep the valve off the piston?). the compression is 138psi in both. I am also wondering if any play(slop) in the wrist pins/bearings is tolerable, when i turn the primary from side to side there is some play before the pistons actually move. I have not taken the engine down but i went in with a scope and everything appears to be in good shape. My main question would be is it worth trying to get the rest of the season out of it, probably 500 more miles, or should i tear it down and rebuild?

02-24-2012, 04:35 PM	#4 (permalink)
shagsmc Advanced Member Join Date: Nov 2009 Posts: 44 Current Sled(s): 2008 Switchback 600 Previous Sled(s): 94 Indy Trail 500Fan - 85 Indy 440Fan Location: Northern Ontario Favorite Riding Area: On snow 10-11 Mileage: 14 Age: 25 Riding Since: 1994	I am a little concerned about my 08 600 Switchback, 5000 miles with 200 engine hours. After reading this I'll probably tear into it this summer. __________________ 2008 KTM 200 XC-W

02-23-2012, 02:12 PM	#2 (permalink)
Michiganstopcat Super Advanced Member Join Date: Feb 2003 Posts: 815 Current Sled(s): 03 edge/xcr Location: 48835 Favorite Riding Area: Michigans Upper Penninsula Age: 40 Riding Since: 1995	Run it you have plenty of time in the summer to rebuild no use in wasting good riding time!! Like they say it will go or blow either one is fun in its own way!

02-23-2012, 03:59 PM	#3 (permalink)
JP33 Super Advanced Member Join Date: May 2006 Posts: 2,031 Current Sled(s): 2013 Pro-R6 Previous Sled(s): D8, IQ6, XCSP6 Location: NY Favorite Riding Area: In The Woods... 12-13 Mileage: 1160 11-12 Mileage: 732 10-11 Mileage: 1538 Age: 43 Riding Since: 85'	With those comp numbers and finding nothing bad during your visual inspection, I would run it and deal with it in the off season. There's not much left anyway.

02-24-2012, 10:30 PM	#5 (permalink)
poo boy Super Advanced Member Join Date: Jan 2004 Posts: 1,424	Can you explain what the washers accomplish? The valve land still sits on the cylinder land.

02-25-2012, 07:58 AM	#6 (permalink)
fastsleddr Super Advanced Member Join Date: Apr 2006 Posts: 7,922 Current Sled(s): 09 685 shift / Barney / 06 fuse Previous Sled(s): Lots of everything Location: Beaver Dam, Wi. Favorite Riding Area: the bedroom YEEHAW!! 12-13 Mileage: 1930+ 11-12 Mileage: 1700+ 10-11 Mileage: 1945+ Age: 50 Riding Since: 1968	BIGGEST concern with the 600 HO carbed motor is--the oil pump drive gear on the crank. They like to wear out at about 6000 miles.( I've seen this many times as I've rebuilt many) I would run it the rest of the season, than tear it ALL THE WAY DOWN. and inspect the crank gear!! Poo---In my research and engine rebuilding I found a place that drills into the cylinder and installs a stainless steel exhaust valve stop. Can't remember who at this time. The reason the exhaust valve scuffs the piston is the stop in the cylinder, and the stop on the valve get worn. You can remidy this by grinding some extra clearance on the exhaust valve.

02-25-2012, 09:15 AM	#7 (permalink)
978alwaysbroken Newbie Join Date: Nov 2010 Posts: 7 Current Sled(s): 08 IQ shift 600 Favorite Riding Area: pittsburg 10-11 Mileage: 2500 Age: 33 Riding Since: 2005	I will be grinding the valve and running it for the rest of this season. Thanks for the heads up fastsleddr, i have yet to hear that in all my research on my sled, I plan on taking it all the way down this summer, and my hope is that i can 660 her( so long as i can scrape up the $).

02-25-2012, 03:22 PM	#10 (permalink)
IQPolarice Super Advanced Member Join Date: Feb 2011 Posts: 549 Current Sled(s): '12 Switch Pro-R 600, '10 Shift 600 Previous Sled(s): '07 IQ 600 carb (spare) '99 XCSP 700 Location: Northwest OH and Central UP Favorite Riding Area: West Hiawatha National Forest 12-13 Mileage: 1200 11-12 Mileage: a lot 10-11 Mileage: 1250 Age: 34	I have an '07 carb with 7500 miles on it. Do you think I should rebuild? I did have an issue at the beginning of the season with both exhaust valves missing about half. That was when we cleaned them from last season.

Remove Advertisements Sponsored Links
Hardcore Sledder Snowmobile Forums Advertisement