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increase the stock compression ratio
Posted: Wed Nov 07, 2001 5:55 pm
by bkowal@cgocable.net
The stock KLR has a mild compression ratio of 9.5:1. Most other
large "performance" singles (KTM and KLX) are in the 10.5 to 11.0
range. Boosting to 11.0:1 would give an easy 16% performance gain. I
figure by running premium gas, the general robustness of the engine,
the water cooling and by adjusting other tuning items (jetting and
plug tempuratures) the reliablilty of the engine would not be
reduced.
The question is what is the most effective way to boost the
compression. The easiest way would be to replace the stock piston
with an aftermarket performance unit. I have been unable to find a
high compression piston for the KLR. I have noticed that the KLX 650R
has a 10.5:1 ratio. Maybe the piston would fit in the KLR to give it
a boost. It seems to have the same basic dimensions. Has anyone ever
tried this?
The other choice would be to mill the head and possibly the piston to
provide more valve clearance. I figure aroung 1 mm would have to be
taken off. Has anyone does these mods? What would a performance shop
charge for this kind of work?
If you are prepared to run premuim gas all the time this could be the
best bang for the buck to get another 6 HP out of her.
increase the stock compression ratio
Posted: Wed Nov 07, 2001 6:37 pm
by Stu
--- In DSN_klr650@y..., bkowal@c... wrote:
SNIP
> The other choice would be to mill the head and possibly the piston
to
> provide more valve clearance. I figure aroung 1 mm would have to be
> taken off.
SNIP
This seems an easier mod than piston replacement just off the top of
my head, but I have a couple of questions;
What effect would this have on the cam timing chain?
1mm doesn't sound like much, would the tensioner just take up the
slack?
As a side note, premium fuel here in CA is now only 91 Octane. Used
to be 92 until this June.
Cheers
CA Stu
increase the stock compression ratio
Posted: Wed Nov 07, 2001 10:49 pm
by Devon Jarvis
I have a 10:1 piston in one of my SR500s (stock is 9:1) and it does indeed
make a difference. I don't know the differences between the KLR and KLX
motors, but the old-fashioned milling the head is a common practice.
Remember not only will you have to deepen the valve pockets, but the cam
timing will be retarded and you will need modified cam sprockets.
There's a guy on the Thumper list who does work like this, Hoyt McKagen. I
have never used his services personally, but have heard good things about
his work. He has given me lots of good advice about my SR500 in the past.
http://batwings.freeyellow.com/best.html
An old issue of DSN has an article about hopped-up KLR motors, the guy who
built them did compression, bore, stroke, you name it. Don't have the issue
handy (or therefore his phone number) but hopefully he's still out there.
Anyone else have the back issues handy?
Devon
bkowal@... wrote:
> The stock KLR has a mild compression ratio of 9.5:1. Most other
> large "performance" singles (KTM and KLX) are in the 10.5 to 11.0
> range. Boosting to 11.0:1 would give an easy 16% performance gain. I
> figure by running premium gas, the general robustness of the engine,
> the water cooling and by adjusting other tuning items (jetting and
> plug tempuratures) the reliablilty of the engine would not be
> reduced.
>
> The question is what is the most effective way to boost the
> compression. The easiest way would be to replace the stock piston
> with an aftermarket performance unit. I have been unable to find a
> high compression piston for the KLR. I have noticed that the KLX 650R
> has a 10.5:1 ratio. Maybe the piston would fit in the KLR to give it
> a boost. It seems to have the same basic dimensions. Has anyone ever
> tried this?
>
> The other choice would be to mill the head and possibly the piston to
> provide more valve clearance. I figure aroung 1 mm would have to be
> taken off. Has anyone does these mods? What would a performance shop
> charge for this kind of work?
>
> If you are prepared to run premuim gas all the time this could be the
> best bang for the buck to get another 6 HP out of her.
>
> Checkout Dual Sport News at
>
http://www.dualsportnews.com
> Be part of the Adventure!
>
> Visit the KLR650 archives at
>
http://www.listquest.com/lq/search.html?ln=klr650
>
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>
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http://docs.yahoo.com/info/terms/
increase the stock compression ratio
Posted: Thu Nov 08, 2001 12:13 am
by twowheelwandering@yahoo.com.au
>
> An old issue of DSN has an article about hopped-up KLR motors, the
guy who
> built them did compression, bore, stroke, you name it. Don't have
the issue
> handy (or therefore his phone number) but hopefully he's still out
there.
> Anyone else have the back issues handy?
>
> Devon
>
That would be Steve Kesselring, very knowledgeable guy. Don't know
if he's still into messing with KLR's like he originally was but
doesn't hurt to ask. He coated a bunch of components for me and
worked out a way to make the lower first gear mod work with a post 96
gearbox. His shop is
www.qualityengine-rd.com
Rich
> bkowal@c... wrote:
>
> > The stock KLR has a mild compression ratio of 9.5:1. Most other
> > large "performance" singles (KTM and KLX) are in the 10.5 to 11.0
> > range. Boosting to 11.0:1 would give an easy 16% performance
gain. I
> > figure by running premium gas, the general robustness of the
engine,
> > the water cooling and by adjusting other tuning items (jetting and
> > plug tempuratures) the reliablilty of the engine would not be
> > reduced.
> >
> > The question is what is the most effective way to boost the
> > compression. The easiest way would be to replace the stock piston
> > with an aftermarket performance unit. I have been unable to find a
> > high compression piston for the KLR. I have noticed that the KLX
650R
> > has a 10.5:1 ratio. Maybe the piston would fit in the KLR to give
it
> > a boost. It seems to have the same basic dimensions. Has anyone
ever
> > tried this?
> >
> > The other choice would be to mill the head and possibly the
piston to
> > provide more valve clearance. I figure aroung 1 mm would have to
be
> > taken off. Has anyone does these mods? What would a performance
shop
> > charge for this kind of work?
> >
> > If you are prepared to run premuim gas all the time this could be
the
> > best bang for the buck to get another 6 HP out of her.
> >
> > Checkout Dual Sport News at
> >
http://www.dualsportnews.com
> > Be part of the Adventure!
> >
> > Visit the KLR650 archives at
> >
http://www.listquest.com/lq/search.html?ln=klr650
> >
> > Post message: DSN_klr650@y...
> > Subscribe: DSN_klr650-subscribe@y...
> > Unsubscribe: DSN_klr650-unsubscribe@y...
> > List owner: DSN_klr650-owner@y...
> >
> > Your use of Yahoo! Groups is subject to
http://docs.yahoo.com/info/terms/
increase the stock compression ratio
Posted: Thu Nov 08, 2001 9:02 am
by TLrydr@aol.com
In a message dated 11/7/01 11:50:16 PM EST, jarvisd@... writes:
<< An old issue of DSN has an article about hopped-up KLR motors, the guy who
built them did compression, bore, stroke, you name it >>
Where can i get a copy of this mag, I have been signed up for the
DSN for the last 2 years, an't seen that issue. Matter fact i have not seen a
issue in a long time now.
Mike
increase the stock compression ratio
Posted: Thu Nov 08, 2001 9:33 am
by Devon Jarvis
The KLR727 and KLR770 project articles are on the back issues CD, I
bought it from DSN and printed it out myself. I forget how much the CD
cost but it wasn't much, and I thought it was really worth it.
Devon
TLrydr@... wrote:
increase the stock compression ratio
Posted: Thu Nov 08, 2001 3:39 pm
by BCSavWill@cs.com
Hi,
I have been down this road and at some time in the future will get some
pistons made, they work out cheaper than stock too and are forged. The quotes
I have had are for a batch of 4 with a pattern needed. Any bore oversize and
CR in batches of 4.
Price complete with rings and pin $155 against Kawa $175 but there is
shipping and handling.
If the liner will take a 3mm overbore you would get about 690 cc. 2mm is
678cc and 1mm 665.
To use a KLX piston you need the R model one at 10.5 cr and this is designed
for a nikasil bore (closer fit) by a lot (in piston terms) I have writen
about this before, maybe check the archives. Also the included valve angles
are different so the valve pockets will be different, don't know about valve
diameters but ther KLX KLR par #'s for piston and valves are different for
the KLR and KLX and KLX 'R'.
Brian
KLR A14
KLX C1
TE 410E
Honolulu, HI
[Non-text portions of this message have been removed]
lots more tire questions....
Posted: Fri Nov 09, 2001 9:39 am
by Arden Kysely
I'm hoping to get them off before it rains here in SoCal. I get
enough of the near-death stuff from the brain-dead drivers trying
to 'borrow' my lane.
Arden
--- In DSN_klr650@y..., k650dsn@a... wrote:
> --- In DSN_klr650@y..., "Arden Kysely" wrote:
> > I've got the Dunlop D606 on the rear and the K139 (now also a
D606)
> > on the front, and they definitely add to the vibes on the street.
I
> > did 1000 miles of 50/50 riding on them in Utah, plus maybe
another
> > 700 assorted miles and the rear is noticeably wearing down. I'd
> > estimate it will be toast in another 800 miles. They work great
in
> > the dirt, but I've had some small slides on the street with the
rear
> > kicking out under power on corners. Braking suffers some, too.
I'd
> > say they're best left to those who live close to the dirt and go
> > there often. In the city, I'd like more traction.
> >
> > Arden Kysely
> > A11 "Mr. K"
> >
>
> If you really want a near death experience, take them out on wet
> pavement. They really get lively then.
>
> Gino