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Which Big Bore Kit?

29K views 12 replies 8 participants last post by  PeteK  
#1 ·
I have some minor piston & cylinder damage from air filter issue.
I plan to install a 685 or 692 kit. Thinking of the $299 US, 692 kit from EagleMike.com
Would probably send them my cylinder for re-bore too. $114 US

Should I consider other brands / suppliers?

Bike only has 7000 Miles...

Thanks,
Jack
 
#2 ·
There are a couple of schools of thought on the topic.
1) Go at this inch by inch, if you go with the 685cc, you can later rebore to 692cc when the 685 wears out, etc., etc., etc.
2) Go big and don't worry about wearing the bore out - you can find another cylinder for $100-200 on ebay and repeat the build when the 719cc wears out.

I think it depends our your cash flow and maintenance skills. If you're anal about checking your air cleaner, airbox, hoses, religious about oil changes and valve checks, then go for the 719cc kit, and enjoy the extra zip. The 719cc kit will also need the sleeve and rebore - which pushes that total to over $800, with shipping & taxes.

But even the 685cc kit with an opened airbox (L-cutout), KLX or other re-jetting, and a decent pipe (Leo or other), does make more power and runs smoother/less vibes than a completely stock KLR.

There are other sources, such as Jegs and Schnitz, and other makers, e.g., long time manufacturer Wiseco makes a decent piston. The EM parts do have coated skirts and I imagine that this significantly reduces wear over the long term.
 
#3 ·
1996 thru 2018 cylinders will readily accept the EM685 & smaller kits. You might even think about the Wossner 11:1 compression pistons (high octane fuel Always Required thou).

I concur with 'foo', reserve the 692 size just in case you have another air filtration issue.

Did your exhaust pipe melt the underside of your air filter box wide-open? Or something else happen?
 
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#4 ·
I recommend the Eagle Mike 692cc kit. BIG performance gain as measured by the seat of my pants. Also deeper and louder exhaust note.

I bought an eBay cylinder for $75 and sent it to Eagle Mike for boring and honing while I continued to ride my bike. Then when I received the cylinder complete with piston and gaskets, I tore the bike down and installed the big-bore kit in a day. I lost virtually no opportunities to ride the bike by buying a used cylinder and I saved my original cylinder for future use, if necessary.

Jason
 
#6 ·
First, Big Thanks to all who offered advice & Help!

Last summer I rode the Trans Wisc Adv Trail, I was following a big KTM on gravel roads & having fun playing flat track racer around all the bends. I had the darn thing redlined constantly. It Was the 1st trip riding my 1st KLR & I was amazed at how slow the darn thing is!! Could hardly get rear wheel spinning in gravel to slide around (BTW VERY Dusty). I made it 60 miles from Lake Superior when guy behind me mentioned all the smoke coming from exhaust. I turned & headed toward home, burned 4 its of oil in 150 miles!! But no engine mechanical noise heard.
So, that was my situation, expected to find something really bad upon disassembly.
Findings:
1) Uni brand Foam air filter was filthy - outside AND inside. I dont think the previous owner applied ANY filter oil to the Uni. I Bought bike w/ 5000 miles, & it had newish filter in it & thought all was fine - Shame on me!
2) Piston & bore are not nearly as bad as I expected, light scuffing. I think I could install rings, hone & use as is.
3) Pulled head - horribly carboned from burning all that oil, But no apparent or catastrophic visible damage. I was perplexed, what the heck IS the issue??
4) Poured kerosine in all 4 ports, it ran freely thru the rt Ex valve. I removed valves, both ex valves & seats aren't sealing, but no significant issue. IE no bent valves, cracked seats etc.

Conclusions:
1) I need Valve job & could use advice on where to take or send head (I am in Chicago area)
2) Decide whether to hone cylinder and replace rings or Buy the Big Bore kit - I hate to spend the $$ needlessly, but the kits sound great, so probably will get one.
3) Install or implement other Mods I am learning about - Airbox, Carb needle, Muffler Mod or new pipe. And anything else that easy & cheap.

Thanks again, need to find a machine shop...

Jack
 

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#9 ·
First, Big Thanks to all who offered advice & Help!

Last summer I rode the Trans Wisc Adv Trail, I was following a big KTM on gravel roads & having fun playing flat track racer around all the bends. I had the darn thing redlined constantly. It Was the 1st trip riding my 1st KLR & I was amazed at how slow the darn thing is!! Could hardly get rear wheel spinning in gravel to slide around (BTW VERY Dusty). I made it 60 miles from Lake Superior when guy behind me mentioned all the smoke coming from exhaust. I turned & headed toward home, burned 4 its of oil in 150 miles!! But no engine mechanical noise heard.
So, that was my situation, expected to find something really bad upon disassembly.
Findings:
1) Uni brand Foam air filter was filthy - outside AND inside. I dont think the previous owner applied ANY filter oil to the Uni. I Bought bike w/ 5000 miles, & it had newish filter in it & thought all was fine - Shame on me!
2) Piston & bore are not nearly as bad as I expected, light scuffing. I think I could install rings, hone & use as is.
3) Pulled head - horribly carboned from burning all that oil, But no apparent or catastrophic visible damage. I was perplexed, what the heck IS the issue??
4) Poured kerosine in all 4 ports, it ran freely thru the rt Ex valve. I removed valves, both ex valves & seats aren't sealing, but no significant issue. IE no bent valves, cracked seats etc.

Conclusions:
1) I need Valve job & could use advice on where to take or send head (I am in Chicago area)
2) Decide whether to hone cylinder and replace rings or Buy the Big Bore kit - I hate to spend the $$ needlessly, but the kits sound great, so probably will get one.
3) Install or implement other Mods I am learning about - Airbox, Carb needle, Muffler Mod or new pipe. And anything else that easy & cheap.

Thanks again, need to find a machine shop...

Jack
If youre looking for a cylinder guy in the chicagoland area ive used Micron engine and machine in Stone Park. I was happy with the results on my XT350, he did the valves and bored the cylinder.
 
#7 ·
Late to the party but;

- 1) IMO Eaglemike's kits are the most advanced and the best value

- 2) 719 is great but requires a new sleeve so the cost is significantly more - Unless you are doing a full on effort to eek out as much power as possible, I'd stick with the 685 - 692

- 3) The higher compression kits are not as advanced a design and I value the ability to run on any crap gas available so that personally steers me back to the 685/692

- 4) with regards to the 685 vs. 692, I went 685 so that I can rebore my cylinder to 692 in the future.....sure you can buy another cylinder but for the extra 7cc's, physics suggests the difference between the 2 kits is less than 1hp......but they are both good choices, just explaining my logic.

As far as your thoughts go, I'd caution that a hone/ring replacement seldom works to solve the oil burning issue which is related to both bore distortion and poor ring design - boring the cylinder restores it to round (and the "seasoned" bore tends to stay that way) and the EM kit has far superior rings. Trying to bandaid it is highly unlikely to solve your propblem and you'll end up pulling it all apart twice.

I can tell you that a 685 plus the usual mods: snorkle removal, L-mod, jet kit, uni-filter (oiled properly!) and optionally, the silencer of choice (I recommend the LeoVince X3) will give your bike a noticeable boost in power and torque, you will no longer have oil burning issues, the bike will run properly, cooler and with less vibration.






Cheers,
Dave
 
#8 · (Edited)
Ditto Paul’s and Dave’s comments. For the amount of work and cussing involved, don’t try to cheap out on the parts. Send everything to EM and let him bore/hone and recondition the head. Grand total will be around $700 with shipping both ways. I wouldn’t mess with trying to find a local machine shop either. EM has done this job 100’s of times and has more experience than anyone else.
 
#13 ·
When you get the parts back from Micron, you will need to check and set the valve clearance with new shims. If you coordinate with Micron, you probably can have them “tip” the valve stems a (grind off a few thousandths) to get the clearance right for the shims you have.

I should have pointed it out before, but for future reference for anyone reading this thread:
When Eagle Mike reconditions your head, his machine shop sets up the valve clearances too, by grinding the valve seats to the same depth, by tipping the valves so they are the same lengths, and then providing new shims for correct valve clearances. I doubt most general automotive machine shops do all that unless you specify exactly what you want them to do. Also EM has KLR valves in stock, so if you need new valves, the shop doesn’t have to wait for them (in my case, I had one burned valve, and the other was in poor shape so we replaced both exhaust valves at $58 each). I measured everything when I received the parts back from EM, and all the measurements were within the new specs.

Bottom line: wherever you get your machine work done, measure everything when you get it back. Test assemble the cams and caps on the head and check the valve clearances, before you bolt the head on the engine.

Speaking of measurements: make sure you set your valve clearances on the LOOSE side of the spec, especially the exhaust valves. As the valve/seat wears, the clearances reduce. Too little clearance will lead to a burned valve. Better too loose than too tight. That’s part of why the exhaust clearance is greater than the intake clearance (the other part of the reason is to account for the thermal growth of the valve stem when it gets hot).