[Bruce CurtisMember]

Your photos are pretty ordinary considering your profession Michael!!!

Me myself and I reckon it’s a combination of two things, I;ll wait and see what the knowledgeable laddies say.

For the fix, I’d send it to Eric Gorr and for similar money to a straight replate you can get a pretty good well dialed setup, to back this I am sending mine to him at replating time for a B/Bore, torque porting and replate for around the same as Electrosil want just to plate here.

http://www.eric-gorr.com/index.html

That regime you were boasting of Mick……Mmmm bitten right on the arse by it eh?

[Bruce CurtisMember]

menace wrote:

Quote:

rhank you bruce. i was waiting for that :laugh:

“ok you late model KTM & Suzuki RM lads can run off now, nothing more for you lot here.”

reading into that bruce, one might be lead to believe that these are somewhat superior engines,
with cleaner burning, better engineered and designed porting and chamber surfaces out of the factory and reletively spooge free running, with better economy as well.

but is spooge good for anything though, except catching fire? :laugh:

Hey Menace, the only thing you didn’t mention was POWER, it appears that the class leading engines in the POWER and delivery of this POWER are all heavy duty Spoogers, the TMs famous for their brutal delivery once unleashed, the CR250R honda second only 2T in the area of INSTANT boogie to the YZ250s, the KX500s and CR500s the same deal, it appears it has something to do with the port configuration, much like the timing overlap in a high-performance V8, their equivalent is flames on the overrun, ours is spooge almighty, it does burn well if you get it hot enough I know this for sure and you witnessed it after Mick brought mine back from his high speed shenanigans that day, smoking like a Winfield Ad.

BC

[Bruce CurtisMember]

TB has the good oil for you here Mr Menace, it’s the float level, the problem is not starvation but flooding if it is going downhill, you see most of us running Keihin Airstykers or the likes are in a hard place with this one. The floatbowls are of very limited volume and if you set the level low enough to eliminate flooding on downhill runs you will experience momentary starvation elsewhere. If it is indeed Starvation (less likely but does happen) on downhill runs raise the float level not by factory specs, but by holding the carb body vertical and adjusting the needle to open just above dead level, shouldn’t need rejetting and should cure any starvation.

Part II of your Q, as stated reroute hoses to airbox or up frame somewhere, put a “U-Bend” in them helps too.

BC

[Bruce CurtisMember]

Well i spent a few hours today cleaning up the worst cast barrel I have ever touched, the ports were all wildly mismatched, casting dags all over it, so me and the die grinder and a dremel played for a while and basically blueprinted the intake/exhaust and then I matched the exhaust and might do the cases yet.
Am going to skip the piston/port mod on this one, he doesn’t need any more topend, but after carefully scrutinising the whole port relationship I ended up cutting two new transfer ports/channels into the bottom of the rear transfers, should assist in midrange airspeed and give better throttle response.

Might advance the timing 1-2 degrees and space the pipe out a few mm to give it a longer header section to improve torque at lower-mid as well yet, only prob is since I sold my lathe I might have to scrounge something up.

Told the young bloke she’ll be brunning tomorrow arvo, stronger and sweeter

[Bruce CurtisMember]

white rocket wrote:

Quote:

Mr Blue wrote:

Quote:

e in wide ratio g/box to make it next to gods own bike IMHO.
Just happen to have acquired a WR450 gearbox just for that reason.

BTW I seem to remember to YZ250s stopped having a 6 speed box around 1981.

Bruce C.

hay mr blue if you put a wide ratio box in your bike i bet you hate it you will be in and out of band and out of control everywhere thats what i hate about modern endero two strokes(sorry just my opionin a 4stroke rider thats riden 2strokes most of my life that loves the close ratio boxs you don t have to rev the crap out of them to stay inband)

Hey Rocket, at this stage I’m going to try 3rd/4th/5th only, leave 1st and 2nd original, this will give a close ratio bottom three (third on the WR450 is a bees dick shorter than the original YZ. Thr fifth gear is a big ratio jump so I should have the best of both worlds, a very close bottom three, a little different into fourth 9not a huge gap tho’) and a substaintial 5th overdrive, combine this with an overall drop in final drive ratio and my very responsive off idle powerplant should be something like perfect for me.
If not just play until I get it right.
But you are right the 300excs gearbox gives me the irritts, as it feels very agricultural, no real smooth through the gears feel.

BC

[Bruce CurtisMember]

Nah not behind in your thinking, it was an anomaly in those years, I think the Yamaha R&D blokes
(back when they actually had some) found a better configuration from an existing base design,
and the WR250 ended up with a much more responsive powerplant. I think you’re right it may be O’ringed,
the ’92 YZ was a gasket from memory, but they did change it somewhere in that era.
The runon or pre ignition is signs of excessive coke or lean fuel delivery,
having said that it could come back to plug again holding a glow from being the wrong heat range.
Check the burn pattern in the combustion area, it may need massaging to get a better flame spread.

Someone above made a reasonable (for a 4t) suggestion of some fuel system cleaner, personally would never use it
on a 2T, tends to dissolve the residual oil in and around the lower end, something you usually
try to avoid. And stick to normal pump fuel, higher octane tends to make them run a bit funny unless specifically
tuned for it.

Welcome to the church of the manic 2 stroke dirtbike where we don’t need to sacrifice valves to any diety…………..

BC

[Bruce CurtisMember]

Hey Mr 454 (big block chev?) no offence is taken or noticed, anyway you know how your WR comes on the power fairly early and hard, well the similar model YZ comes on a bit softer and a little later, yamaha seems to have put a supercross engine in the WR and a cross-country/MX engine in the YZ. Checking the spark by kicking it over in the shed just gives an indication of the low speed windings, the high speed windings should be bench tested. Anyway I don’t think it’s the issue anyway as it has not done it on the fresh mix, if I was you I’d pull the barrell intact and clean the p/valve assembly and maybe decoke the head if needed (that model YZ has an awful squish and burn pattern, but the WR may be diiferent as the comp ratio was different too), if the rings are good and everything else is in order just a head and base gasket.

My YZ250wr, well the late models have INSTANT and mean INSTANT boogie, mine has a large flywheel weight to slow it down a little in delivery, doesn’t boil, but shows signs of “hotspotting” in really nasty tight single track, fully roadworthy curbweight is around 103 kg, terrific bike just needs a wide ratio g/box to make it next to gods own bike IMHO.
Just happen to have acquired a WR450 gearbox just for that reason.

BTW I seem to remember to YZ250s stopped having a 6 speed box around 1981.

Bruce C.

[Bruce CurtisMember]

Trailboss wrote:

Quote:

Mr Blue wrote:

Quote:

TB is right there are some excellent cost effective oils out there, find one, stick to it and a ratio, jet to suit and set and forget until the seasons change then raise the needle (drop the circlip) a notch or two for your off -idle and midrange response.

BC

Dont think it was me Bruce, I dont do any smoker advice. Motul has the best product range on the market in my opinion

TB

Sorry didn’t look at the avatar properly, was Ollie, just saw a splash of red and jumped…. :blush:

I like Motul in 4Ts excellent stuff in my old GSXR and the rotary, but for 2T there is plenty of excellent stuff which is more cost effective and some that aren’t…

BC

[Bruce CurtisMember]

You have isolated the issue, Thick old valvoline lawnmower 2T oil (except that’s not what the bottle says eh )
Silkolene is the ducks guts of race oils IMHO, it’s lubrication and dispation properties are terrific, but is overkill for us old hacks on trailriding.

Menace knows me well enough now to guess i will disagree, Eric Gore through exhaustive testing found recently that the most power was developed at a ratio of 18:1, and progressively gets worse up until around 35:1 thereafter it made no difference.

I would say that the WR250z powervalve assembly was gumming up a little or “slow” on the valvoline, and being basically a more agressive version of the then YZ engine (true more agressive yep) the powervalve assembly is the same which doesn’t like stiction. The jetting may ahave been an issue as well, but remember the difference between 50:1 and 25:1 is only a mere 2% of combustibles, this is less variance than a melbourne afternoons woth of weather would have on your A/Fuel ratio. Going to basics i would suggest for your bike to react so noticably to a imperceptable adjustment to the Oil/Fuel ratio is either:

1-Jetted right on the edge of optimum
2-Is running a plug too cold for the conditions
3-Has weak spark on the HS windings
4-has a fairly heavily gummed P/Valve assembly which is creating friction as the burn is hotter from issue #1

TB is right there are some excellent cost effective oils out there, find one, stick to it and a ratio, jet to suit and set and forget until the seasons change then raise the needle (drop the circlip) a notch or two for your off -idle and midrange response.

BTW I run 25:1 on “red mist” rides and 33:1 for funtimes, spooge is NOT caused by oil but by rich jetting or unburnt fuel………….

BC

[Bruce CurtisMember]

Is that a Poulan unit you’re using oh Large Purple one?

If so where did you buy the attachment?

BC

[Bruce CurtisMember]

One of the worst handling bikes ever made were the early alloy framed Cr’s, excellent motor (CRs always did have) but far too stiff lent over and transferred everything to the rider.

Even McGrath stayed on the steel frames for a few seasons into alloy……

BC

[Bruce CurtisMember]

Yeah as Mick said best not to, it’s a bit rude seeing as they’re giving OBT exposure, just tell everyone to rush out & buy their own copy.

Polka dots eh??

Was there polka music?

BC

[Bruce CurtisMember]

LC4skin wrote:

Quote:

I love bike maintenance, I go in the shed thinking ill just fix my radiator that nearly got torn off last weekend, next thing you know 3 hours have gone bye. Ill just fix this and this and this and this. Anyway what else am I going to do?

Typical KTM rider, time means nothing to them, which is why they are convinced that orange is fast.

Three hours crikey LC$$ the little chinee bloke who made the radiator in the first place woulda made 50 in that time, from bare coke cans and an open fire…..

[Bruce CurtisMember]

Ollie wrote:

Quote:

LC4skin wrote:

Quote:

Check this out Ollie and all the Gasser riders

Christophe Nambotin special 300

– Ohlins TTX fork cartridges
– Ohlins TTX shock
– Interchangeable cylinder head
– Renthal handlebars
– FMF muffler
– Gold-coloured frame
– Wave discs
– Crankcase protector
– Nambotin graphics
– ADR approval

15 of 200 coming to Aussie, Graphics are a bit out there though :laugh:

Ollie

Nah that is a good looking gasser, I’d be proud to park one in the shed, especially if it goes as well as the spec’s suggest.
$15K for a dirtbike is a bit outa my comfort zone though…..

[Bruce CurtisMember]

It’s as i suspected TB, different riding habits, My roadie helmet is a very very quiet top of the line (in 1998) Shoei, as the wind noise riding the country roads at “speed” is a bugger.
I have never thought about it on the dirtbikes as I actually like the sound as part of the sensory input, but as you said you’d get used to it…. might give it a shot see what it’s like.

Bruce C

[Author]

Posts