Recommended engine mods - Kawasaki KLR 650 Forum
1987 to 2007 Wrenching & Mods For maintaining, repair or modifications of Generation 1 KLR's. 2007 and earlier.

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post #1 of 15 Old 02-04-2016, 03:48 PM Thread Starter
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Recommended engine mods

Hi everybody. I'm totally rebuilding my klr engine, I'm going for a 650 engine (as I got one in the big boxes a parts I got with the bike). I've moved the bottom engine mount already. just the front one to make.
In the engine parts to choose from, there's both 600 and 650 cams and gearboxs so I'm well up testing different combinations.

On a side note the cam that the decompressor has snapped off (after it the bike got stolen) is 180 degrees out compared to the other 3 cams I have, I had four cams when I first built the 600, one dead one, three good ones, but I only know which set is 600 the others are a mystery!!!! lol. But never noticed any difference until the other day!!!!

Thanks
Ian
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post #2 of 15 Old 02-04-2016, 06:17 PM
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Quote:
Originally Posted by Ian H View Post
Hi everybody.

On a side note the cam that the decompressor has snapped off (after it the bike got stolen) is 180 degrees out compared to the other 3 cams I have, I had four cams when I first built the 600, one dead one, three good ones, but I only know which set is 600 the others are a mystery!!!! lol. But never noticed any difference until the other day!!!!

Thanks
Ian
Ian,
"180 degrees out"?

With the sprocket dowel pins pointing 'UP' an Intake Cam will have the lobes pointing rearward.
An Exhaust Cam will have the lobes pointing forward.
An Aftermarket Exhaust cam will Not Have a de-compressor.

People have been known to accidently attempt to use an in-appropriate cam in the wrong spot.

pdwestman
Modify at "YOUR OWN RISK"!

Still riding my 1987 KL650-A1. 85,000+ miles & counting
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post #3 of 15 Old 02-04-2016, 06:39 PM Thread Starter
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I'll try an take some pics tomorrow an pm the to you if your interested or pm you the links, I got flu at the mo so cant do much.

Cheers
Ian
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post #4 of 15 Old 02-07-2016, 06:40 PM
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I'm in the process of putting a kl600 tans into the 650, per this page. The Kawasaki KLR650 Projects Supposedly a lower 1st and 2nd, same 4th and 5th. Supposedly swaps right in. I'll take pictures and count teeth when I get there, hopefully next weekend.
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post #5 of 15 Old 02-07-2016, 07:18 PM Thread Starter
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Cool, thanks for the link, I'll have a read, I have both gear sets sat in biscuit tins so I'll have a look too.
Thanks

Ian
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post #6 of 15 Old 02-08-2016, 11:57 AM
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Ian H,
Looking at 84-07 manuals and parts diagrams, the 600 exhaust cams up-date to 87-95 650 part numbers.

And 87-07 cams have the same Ex specs.
Open 57* (BBDC)
Close 31* (ATDC)
Duration 268*

2008 and up Exhaust cams have specs of,
Open 57* (BBDC)
Close 37* (ATDC)
Duration 274*
This extended open duration is why the (MC Mod) Exhaust cam advancement works better on 08 and up and sometimes not so well on 2007 and older.

All years of stock 600 and 650 KLR intake cams use same specs.
Open 19* (BTDC)
Close 69* (ABDC)
Duration 268*

pdwestman
Modify at "YOUR OWN RISK"!

Still riding my 1987 KL650-A1. 85,000+ miles & counting
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post #7 of 15 Old 02-08-2016, 07:47 PM
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Thus, a Generation 1 KLR650 upon application of the vaunted MC mod, exhaust valve timing would look like this:

Open 82 degrees BBDC;
Close 16 degrees ATDC;
Duration 268 degrees; Minus 15 degrees valve overlap from stock.

Generation 2:

Open 82 degrees BBDC;
Close 22 degrees ATDC;
Duration 274 degrees; Minus 15 degrees valve overlap from stock.

Some day, science shall answer the question: How does advancing the exhaust cam 15 crankshaft degrees (one camshaft sprocket tooth subtends 7.5 camshaft degrees/15 crankshaft degrees), consequently subtracting 15 degrees of valve overlap, produce additional horsepower across the rpm spectrum?
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post #8 of 15 Old 02-09-2016, 09:44 AM Thread Starter
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Hi, thanks for the cam timing info. I need to look into the mc mod, but I'm guessing its advancing the ex cam one tooth? But as Damocles puts it you loose a load of overlap.

Also, would it be worth getting the head skimmed to increase the compression a bit? I've already cleaned an polished the ports.

Thanks

Ian
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post #9 of 15 Old 02-09-2016, 10:53 AM
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Originally Posted by Ian H View Post
Also, would it be worth getting the head skimmed to increase the compression a bit? I've already cleaned an polished the ports.
In my opinion, YES!

However, KLR hop-up aficionados seem reluctant in addressing increased compression ratio, a proven performance-enhancing technique. Amazingly, some KLR owners will pursue expensive modifications producing at most only a miniscule performance enhancement, meanwhile ignoring less costly, proven effective compression ratio increasing techniques.

While the valve timing will be retarded (minimally) from shaving the head, don't think the fractional angle would make any noticeable/measurable performance impact.
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post #10 of 15 Old 02-09-2016, 12:22 PM
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Quote:
Originally Posted by Ian H View Post
Hi, thanks for the cam timing info.

Also, would it be worth getting the head skimmed to increase the compression a bit? I've already cleaned an polished the ports.

Thanks

Ian
Ian H,
I'd suggest using a Wossner or possibly some other brand of Hi-Compression piston instead of permanently altering the head combustion chamber volume. And then needing to possibly alter valve head clearance pockets on the piston and possibly figure out a way to re-degree the cams.

I believe that the Hi-compression dome of a piston could be machined down if you were to find it's compression ratio was too high. Kind of hard to add material back onto the head gasket surface. IMHO.

I would only 'skim' the head enough to true the surface.
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