705 BB kit - Kawasaki KLR 650 Forum
2008+ KLR650 Wrenching & Mod Questions For repair, maintaining or modifying discussions related to the newly updated 2008 and beyond, Generation 2 KLR650 Motorcycle.

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post #1 of 28 Old 09-07-2011, 08:01 PM Thread Starter
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705 BB kit

After a good deal of research, I think this winter's put away project will be the 705 BB kit. My 09 is using more oil than I am comfortable with on highway trips and the fact that this kit comes with a new sleeve gives me the warm and fuzzies. My question is this: since I am mainly intersted in eliminating oil comsumtion keeping the MPGs up; can I still use my stock pipe with this kit, and how much jettng and air box mods would be necessary?

Thanks all!
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post #2 of 28 Old 09-07-2011, 09:06 PM
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If you want to keep mpg's up I would do the 685. You can run the same jetting as stock. It' will also take care of the oil burning.
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post #3 of 28 Old 09-07-2011, 09:12 PM
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In theory, you could do the big bore kit and change nothing at all. You're going to put a bit bigger jug in between the induction side of the engine and the exhaust side. On each stroke it will bring in a bit more air/fuel mixture, but the ratio, if proper now, will be proper with the big bore kit in place. Similarly, you can push the slightly larger exhaust charge out through the stock muffler with no problem.

Re jetting/re needling and exhaust is not required by the larger volume. Taking maximum advantage of the larger volume requires re jetting/re needling/exhaust.

Make sense?

Oh, and welcome to the forum!

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post #4 of 28 Old 09-08-2011, 06:42 AM Thread Starter
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Thanks Tom! Tons of great information here, glad to be a part of it.
Your theory makes sense; I was hoping it would be that easy.

So I'm here in RI- any members near by?
anyone know of a reputable machine shop?

Thanks guys!
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post #5 of 28 Old 09-08-2011, 10:28 AM
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You're welcome!

Let me poke at things a bit, though. Why do you want to do the 705? The stock cylinders from post '96 bikes are easily bored to accommodate the 685 piston. The 705 is too much, and thus requires a new cylinder liner. In order to safely accommodate the overbore that liner has to be cryogenically treated. It could be said that the 705 is pushing just a bit beyond the reasonable limits for the KLR cylinder.

The 705 will, of course, offer a small margin of performance over the 685 if that is what you're after. It will require porting the head and installing big valves to take advantage of that opportunity, though. It doesn't sound like you want performance so much as to stop the oil consumption (which in my mind is the top 'o the heap, number one, best reason to do the 685/705).

The 705 has a premium cost of a couple hundred bucks if memory serves me right and, when all is said and done, doesn't offer anything over the 685.

Tom

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“On the way downtown I stopped at a bar and had a couple of double Scotches. They didn't do me any good. All they did was make me think of Silver-Wig, and I never saw her again.” -Philip Marlowe

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post #6 of 28 Old 09-08-2011, 12:14 PM Thread Starter
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Poke away man!
All good points. I am partial to the 705 BECAUSE of the new liner- could be more of a mental thing on my part.
I have read that one of the possible reasons for the oil consumption on the new bikes is the cylinder bore gets out of round from extended high RPM running, boring out the exsisting cylinder- it could happen again. The new treated sleeve for the 705 in my mind makes it a bit tougher. This coupled with the even lighter piston than the 685 sold me that this would be the way to go. The extra money seems worth it- as I want to do this once. I'm not so concerned about performance, I like the bike as is, just want some piece of mind as I blast down the highway.
Maybe I'm way off on this- comments are welcome and encouraged.
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post #7 of 28 Old 09-08-2011, 01:03 PM
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No, you're not off base. The 705 is a lighter piston and some have noted that the engine seems even smoother than the 685.

One thing to consider is the addition of a Thermo-Bob. It's backed by a relatively sound theory that the out of round condition may be caused by thermal shock to the cylinder from the way the stock cooling system works. The T-Bob gets the engine up to temp quickly and holds it there pretty consistently.

Now, my experience was this:

I installed the T-Bob very early on. It was on before the onset of really bad oil burning. My bike did turn into a nasty oil burner.

When I tore it down and measured the bore (at a bit over 19K miles) it was nearly perfectly round and straight. In fact, had a machine shop returned a freshly bored and honed cylinder to me within the specs I saw on my used cylinder I would have been pleased with their work.

Did the T-Bob keep it round? I have no way of knowing. It did, on my sample of one, put the lie to the idea that the '08 KLRs burned oil because of out-of-round cylinders. I've always felt that the oil burning was caused by a badly designed ring set.

Tom

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“On the way downtown I stopped at a bar and had a couple of double Scotches. They didn't do me any good. All they did was make me think of Silver-Wig, and I never saw her again.” -Philip Marlowe

“'Why' and 'How' are words so important they cannot be too often used.” -Napoleon Bonaparte

Sting like a butterfly.
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post #8 of 28 Old 09-08-2011, 02:23 PM
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You may have seen this, but if not you might find it interesting...

http://www.klrforum.com/showthread.p...4639#post74639

T

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“On the way downtown I stopped at a bar and had a couple of double Scotches. They didn't do me any good. All they did was make me think of Silver-Wig, and I never saw her again.” -Philip Marlowe

“'Why' and 'How' are words so important they cannot be too often used.” -Napoleon Bonaparte

Sting like a butterfly.
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post #9 of 28 Old 09-08-2011, 05:34 PM Thread Starter
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Tom

Great stuff! I gotta ask, were you to do it over again, would you still go with the 685, or the 705?
The T Bob is on the list, as I am not fond of the radical temp swings. But I gotta say, I am not seeing the oil consumption the other guys are. I've had this bike only three months, and last weekend was the first real test- went camping in limerock CT, the route I took was about 320 miles round trip- took highways all the way back (70-80mph) and had to add 1/2 a quart. Things could be worse.
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post #10 of 28 Old 09-08-2011, 06:19 PM
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As you are considering doing, I did the mod to stop the oil consumption.

Oil is cheap (as LJ often says) but mine had gotten to the point where it could do some damage. I was getting as bad as a quart in 250. Since I often go on long trips (multi day, a couple thousand miles) it was getting to be a real pain as I was needing to constantly check the oil and often had to top off at every fill-up.

I did the 685 and am a self-confessed experimenter and tinkerer. While I was at it I decided to go all the way with a ported head and big valves. I've also got a modified exhaust, intake, and have gone with the KLX needle. I tune with an Innovate LM-2. It could be said that I've gone the whole nine yards. I have The Most Powerful KLR In My Town™.

It's smooth and the passing power from 70-95MPH is satisfying.

Now, I have to freely admit that I believe that the biggest bang-for-your buck mod is the simple 22 cent mod. Money spent after that is analogous toThe World's Fastest Indian. The 22 cent mod gives you 10 horsepower/dollar. The 685 kit, as I did it, gives you .005 horsepower/dollar. I made those numbers up, but I'd wager that a dyno would prove me accurate if not precise. Obviously, then, the 685 should be done for oil consumption, eh?

Were I to do it over again, no I don't think I'd go for the 705. From an oil consumption perspective it doesn't solve the problem better than the 685. From a power perspective it offers even less bang for your buck. Actually, Cary Aspy died before the 705 ever got totally sorted out and from what I have read (Patman's stuff) it didn't really live up to expectations. I know the Schnitz kit and the liner are sorted out, but I never really felt that good about popping the liner and putting one in that is so thin that special heat treatment is required for it to be workable.

There's at least one member here who has done the 705; perhaps he and anyone else with first hand knowledge (rather than opinion) will chime in.

T

Tom [email protected]

“On the way downtown I stopped at a bar and had a couple of double Scotches. They didn't do me any good. All they did was make me think of Silver-Wig, and I never saw her again.” -Philip Marlowe

“'Why' and 'How' are words so important they cannot be too often used.” -Napoleon Bonaparte

Sting like a butterfly.
Noli Timere Messorem

Last edited by Tom Schmitz; 09-08-2011 at 06:34 PM.
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