New member with a not so new KLR 250 (KLR Project)

[crpt]

Hi all forum members.
Joined some time ago, but never left a writen word...just been pocking around   3 months ago I got hold on a 91 KLR 250 (28hp)   . It's not the best machine I had, but it's pretty close. Being simple, cheap, and overall easy do-it-all made me griiim whenever I look at her, and think of what I paid for. My other bike, for the moment is a Suzuki Burgman 400, something completely diferent in everyway you look.And it's taking a pretty good rest, since this Kawasaki came home.
Since bought she's done some >5000km, yes the zeros are right. Done some maintenance, nothing fancy, had a few extras. And last week start rebuilding the engine. Initialy I just wanted to make 2 things. That it really needed. New valve stem seal, and new cam chain idler and rear cam chain tensioner. Everithing else as amazingly fine. But, now comes the "but" , after striping that engine and looking at that four valve head I couldn't resist. So maybe tomorrow I'll finish porting and polishing that head. If everything right, next couple weeks should be time for a complete Namura piston and rings set.
Nothing fancy just good plain old mechanics. I'll try to update whenever possible. Meanwhile here are some images.

At the begining:
 
With mirrors, blinkers and a few more things

[HotShot]

   crpt.   Keep us posted with your repairs & pics.   Don't make yourself a stranger.     

[ghostdancing]

HI CRPT, i'm a newbie as well and from europe as well too (italy).. keep us updated with your job on the pretty nice kawa.. i'm very interested on your porting works.. looks like you are experienced 

regarding your recent muffler change: did you still get the OEM silencer? or you throwed it in the trush? i need one (OEM, used but not badly rusted..)

 

[PonchoV]

Hey 

Not trying to be a damp towel here but the 28 hp rating might be a bit of a stretch.

You'll still have a ton of fun learn a lot about your KLR here.

[TrailRider]

Not trying to be a damp towel here but the 28 hp rating might be a bit of a stretch.

The factory Service Manual, PonchoV, lists the KLR250 engine's power output as 20.6 kw @ 9,000 rpm, or 28 PS (horsepower).

Mathematically, one horsepower is 746 watts; 20,600/746 = 27.61 horsepower; rounded off--28 horsepower.

Granted, that's at the engine flywheel, not the bike's rear wheel, but . . . 28 hp appears a righteous number for a KLR250.

For comparison, a KLR600 engine is rated at 42 horsepower by Kawasaki; Clymer lists KLR650 engines as  47.3 hp @ 6500 rpm (US model); pre-'08.

[PonchoV]

Well pee on me w/ the facts.
My 08 wr250x FI, w/ its up grades dynos out at 29.4 something hp at the rear wheel.
My 08 KLR650 w/ carb, stock pumped out 34.7 hp at the rear wheel.

So a 91 klr250 W/ carb, stock is pumping out 28 hp, even if this is only at the crank, that is a lot of ponies.

Well you have the book Trail, & we all know how to the point you enjoy being.

& I'm thinking you know math.

Well thank you sir.

Senor crpt, I, stand corrected.
Take care & rebuild that 250 cause you are going to own one of the hotest little quarter litre scoot on both sides of the pond.

[crpt]

Hi all
Just received that namura Piston kit I was talking about.  
not much as been done in the bike. But yesterday start to assemble the head, The valves at least. slow work but done with very care  
About that engine yes it's 20.6 KW (28HP), and also yes it's OEM spec for power measured on the crank.

This is how it looked last weekend, this weekend I just moved the crate to another place  

[HotShot]

Keep it up. Please keep us up to date.   

[TrailRider]

Well thank you sir.

You're most welcome, PonchoV!

I derive no pleasure in my correction; nothing personal, and no offense intended, I assure you.

Yet, I MUST defend the honor of the valiant KLR250, the most under-rated dual-sport motorcycle on the planet!

 

[ghostdancing]

..20 KW or 28HP are just numbers.. the little sexy kawa goes well.. but you cannot compare an 1984 born bike with a recent specilized four stroke as the yamaha WRF\YZF or what is her name.. the KLR was the first dhoc liquid cooled enduro .. at her times honda and yamaha made shoc air cooled 250 enduros (yes, these had a superior torque), but were also heavier then the kawa

@crpt: what about this NAMURA piston? it's a larger bore piston or the displacemnt will be the same 250cc? i recently had a talk with Greg (CRW) for a 280 piston kit... maebe the next winter will overbore my 88 girl..for now i'm enjoing her fuel saving ability... gas in my city costs 1,70 EU\liter

[crpt]

Hi all. One more update. This Namura piston set (look- www.namura.com) I bought is almost identical to the OEM one. The diferences are much better finish. And a surface treatment (teflon/molybdenium) on the crown and sides. Hard anodized crown, Etc. Everything else remains the same. Even the rings can be used on OEM piston.
What I probably will do, not sure yet, is to ligthen it just a small amount. And most definitely lower the cilinder 0.3~0.5mm. Then match all ports between head and barrel. But still have to weight the piston and measure the combustion chamber.
This particular one is standard size (74mm). For now, I don't consider going for an overbored. The barrel will be honed and that's it, anyway it's like new.  
Compression ratio will be around 11.8 to 11.9. As I'm looking more to the mild than to the wild side of this engine. This one will be put together to give me many miles not "many headaches". Anyway this litle puppy can make some serious horsepower if that's your intention. I'm also rebuilding with milleage on my mind. The gas cost here (today) is 1.59€. For that and lower rpm on highway I'm already using 16 tooth sprocket with a 42 on the back. 160km/h (indicated) on very favorable conditions of course   , but as could be expected is completely gutless on every other aspect.
Now the pictures: OEM vs Namura both 74mm (STD)

[HotShot]

crpt are you going to do any work on the head, as far as porting or clean up work?   

[crpt]

Yes I will/did  
Here with the valves already on. Sorry no photos for the midle stages of development.
Those ports are very badly finished from factory, but thankfully very easy to work on. Exausth side is incredible restritive. You guys are spending tons of dollars in "ultra,mega,hiper" new pipes when the real bottle neck are those exausth ports.  
Just a small word of advise for someone wanting to do this. The wall under the stud,above the exausth is very very thin. But no trouble the stud might cover it easy.  

Basicaly the head was just cleaned and ported. Exausth and intake side, carb boot included. By the way this head has much room for improvement. That aluminum ports have to much flaws (don't remember the right word). "Dremel" gets the chance to be your best partner at this venture.  
Those black "blurrs" in the valves and head is black ink. The valves where marked and numbered.
By the way that small aluminum bar in front of the head, is my ha-doc (home made) tool to press those valve springs. Two saw cuts and 3~4 bangs with a hammer. And the tool is ready  
Also did a new cam chain idler. 30 minutes with a metal lathe and some teflon, also a new ball bearing to substitut the oem one wich was ready for scrap.



Don't remember if already told but that cam chain idler was the main responsable for opening up that engine. Made one flange bigger than the other.    The ball bearing is a 6001 (12x32x10) sealed, will remove the seals later on. Those copper washer are shims. Works much better then OEM idler.   that started because first the OEM was ready for junk. Second kawasaki here in Portugal asked me 68.98€+IVA(23%) Total 84.85€ (~US$118) what a rip off. And wanted 2 weeks to deliver   Mine works far better then OEM, and was 6€ for the ball bearing everything else free  

[PonchoV]

I use to take the heads to a radiator shop & have them clean out the carbon & the  crud that cakes in the tiny hard to clean corners.

Made the porting easier. 

Are you replacing the valve guides?

[crpt]

Hi.
No those valve guides are in perfect order as most of that engine by the way. Even the OEM piston was in perfect order, less the first compression ring (0.9), and the oil ring (1). The second compression ring still have 0.2 tolerance  
For the cleaning theres nothing better than those powerful chemicals for cleaning ovens and also dishwasher machine rinsing aid (is this the right word?  ) take a look at the oem piston in previous photos, what seems to be dark spots, are in fact dark spots  but made by my dirty hands
Special attention to that exausth valve near "KACR" it's the most beaten one. But even valve seats are in very good shape. In this crappy photos (cell cam) it's hard to see but even the head was polished, and every high spot eliminated.

[HotShot]

crpt your looking good. Are you going to come up with any dyno numbers before and after the rebuild. It would be interesting to see the change in performance.   

[crpt]

Not even close to that. In fact there's a dyno some "klicks" away from my house. But is out of the budget. In the end i'll trust my butt sensibility. It'll be easy to spot any diference in fact with that 16t sprokect you can't miss the diference.

ghostdancing only now I've just read your replyes, sorry. No I don't have OEM silencer, it went strait to the garbage can (Recicle bin  ).
But if your looking for a good and cheap silencer, you have one at home (Italy) Marving makes this simple, cheap, and very efective silencer. see www.marving.com Ref. EDR/24/NC there's also a chrome/aluminum one for 10 or 20€ more.
Take a look at this thread:
http://klrworld.com/forums/index.php/topic,19221.msg229562.html#msg229562

Looks like this

[ghostdancing]

great job and great report.. cant wait to see how she will go... for the muffler: i know the marving.. but like the OEM style; here in italy the bike it's almost rare: has been imported in little numbers during 85 - 88 only and there are very few around (but it's still plenty of KLR600), so to get OEM used parts must look outside italy.

looking forward to get news from portugal!

p.s. you should be really experienced on engine rebuild.. wich were your previous bikes? (except the suz burgman, of course..)

[crpt]

Well by lunch time I hope that cilinder will be 0.4mm shorter  but this time won't be me in the metal lathe
Still not sure if it's worth put that piston in the lathe to remove some more metal. Probably won't do that. The material that can be removed is so litle that it wont make any real diference in weight savings.

Well ghostdancing I've done a few tricks here and there. My best chalenge to time was another italian machine, many years ago I tackled an "Inoccenti De Tommaso" that one came out with 42mm stainless steel valves  . But then i grow up and found out that the most wild engine isn't the best thing on the road, at least for everyday driving. One way or another we grow up, get more mature.

[ghostdancing]

.. i remember the innocenti detomaso,1300cc turbo, was a funny little car; regarding the klr tune up: do you guess overboring (not over 280cc) can lead to problems or an hard to enjoy engine for the everyday use? i would like just a bit more  throttle response\impressive power in the low\middle portion of the powerband... not interested on peakpower\higher rpm improvment.. this mainly because i live in a plenty of hills land, and often have the passenger with me

regarding the intake: wich mods are you planning to your airbox\carburetor?

[crpt]

Any engine well built, maintained and used with conscience. Should be trouble free.
Has can be noticed by description and photos. For the time being I'll not touch that bottom end. But if my option went for a bigger bore I would definitely take a serious look at that part.
In the case of an overboring (280cc for example) don't mess with the OEM compression ratio. There will be plenty of compression just like that. But some head work, mainly clean, polish and porting would be very favorable. It allways is.
On the bottom end new bearings will be a must. Also don't forget that carburetor rejeting.
Depending on the state of the clutch assembly, at least new springs will be necessary.
In general a complet tune up of the bike, should be considered. From brakes, to wheels, tires, bearings, etc. In the end the economical result might not be the most favorable. But you should have a strong and reliable machine. One you can trust and be sure can deliver exactly what you want.
As a rule of thumb: When one consider a power increase in the engine department, should also consider every other aspect of the bike.
There's not much logic in trying to get every bit of power from an engine an then waist it with crappy tires, suspension, brakes and so on.
About overboring to 280cc it's an excelent option. Mainly because you want low and middle end performance. Depending on the "kit" or parts you'll use high end can also gain. 

[TrailRider]

Hi all. One more update. This Namura piston set (look- www.namura.com) I bought is almost identical to the OEM one.

The piston looks great; and--the Namura website advertises persuasively.  However, I'm confused by the Namura application chart.

KLR250 OEM bore is 74.0 mm.

Namura lists no KLR250-specific pistons, but:

KX250, 66.35 to 66.37 mm.
KX250 Nikasil, 66.4 mm
KX250X, 76.95 to 76.97 mm

Reckon the last series listed is the way to go, offering slight oversize.

Which Namura piston did you buy?

[crpt]

If you look closer the photos above you'll see Namura's piston package with ref. 20002PS 

Also look for KSF 250 Mojave. Same thing with extra wheels 

[TrailRider]

If you look closer the photos above you'll see Namura's piston package with ref. 20002PS  

Also look for KSF 250 Mojave. Same thing with extra wheels  

Silly me; didn't even LOOK in the ATV section; let the Mojave commonality slip right past me!

Were I consulting with Namura's marketing team, I'd suggest a double listing of the part for both receptive ATV and motorcycle, or at least, a "slash" notation, as in Mojave/KLR250.

Again, silly me!

 

----------------------


Now for something entirely different, QUESTION:


Are KLX300 pistons compatible (other than bore, piston pin, rings, etc.) with the KLR250 platform?

[PonchoV]

Have a riding bud in Texas who drills the lower part of the piston's skirt. On the o/s of the skirt he would do a light countersink to those new holes.

He said, it not only lightened the piston but aided in lubricating the cylinder walls.

This was only done to air cooled motors.