2troke powerband issue

[alanMember]

think its under 30$ for 4 litres at the depo mate runs it in his ktm 300 he reckon it runs better than the moterex stuff at 120$for 4 litres runs cleaner he reckons

[DeanMember]

wow that is cheap! The Mobil fully synthetic is about $60 for 4 litres from the Depot which is also great value

Ollie

[hillsieMember]

yeah ok will try to find the caltex stuff i onley ran the valvoline cause it was at the servo and diident need to drive the extra 10mins to the local bike dealer. when u work and have to pick kids up and do swimming lessons then feed em time matters lol sure u fellers are in the same boat lol

[DeanMember]

If the bike went good with the oil ratio leaned out to near on what it should be I would finish that bottle off first then grab your other oil when you get the chance, If the Valvoline is full synthetic 50:1 or 2% if semi synthetic 40:1 or 2.5%

Ollie

[alanMember]

[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

[GregMember]

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

[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

[alanMember]

don t like that motul two stroke oil the mineral based stuff makes my lawn mower smoke and pw50 oil runing out muffler cloged the muffler on the jr80 but am a tight arse and going to finish the bottle of.it may be to good a quality and needs to run less of it ?but i do run motul sythetic 4 stroke in the ktm its red so it must go fast

[hillsieMember]

to the suggestion that my sparks not sufficant i fitted my snap on spark plug and it jumpt the 4 mil gap so i rueled out the spark im in agreeance that the power valve may be sticky to which i want to pull the sucker out and clean it up its probly full of oil n gunk but im planing to give it a run with the family over the weekend and attack it during the week im a bit supprised over the aggressiveness of the band i thought thay were ment to be tamer than the yz but i havent ridden a similar model yz so cant comment the onley thing i think it needs is another gear though ive heard thay can be fitted in the case if wanted. i see u ride a yz. how do u find it on the slower trails as mine seems to heat up quick if im puting round waiting for the quads to catch up sorry if im a bit blunt but after afew rums ive been told i can get opinionated i mean no offence

[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.

[hillsieMember]

no big block but its on the cards once the new 871 blower goes on procharger blown 454 sharioff small block at moment(400 rodeck alloy block stroker crank its on the bottle too see photo) righto i must be behind the times a fair bit on my thinking i thought it would be the oppisite for the wr ill whip the barrel off next week anyway and have a sticky as i want to confirm the top end rebuild this bike was suppused to of had(better the devil i know)i onley need a barrel gasket i assume as the head is oringed i think and theres no letter stamp on the head so hopefully ill find somthing on the piston i figured mine was over heating as it was running on after ideleing abitwhen i hit the stopper and it used a bit of coolant after that ride [img]http://www.obtrailriders.com/media/kunena/attachments/legacy/images/019.JPG[/img]

[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

[alanMember]

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)

[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

[Author]

Posts