OzVMX Forum
Marque Remarks => Yamaha => Topic started by: Tossa on May 23, 2009, 08:54:17 pm
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Hi guys, I've got a MX250A and MX360A, have been having problems with fouled plugs, changed from natural based to synthetic, still ran at 25:1. Big probs with plugs. Noticed on another thread that they recommend 30:1 plus autolube. This was from a set of specifications given Latest VMX had good article on oil choices suggesting 40:1 on synthetic
Am running standard jetting 260 main jet on 250 and 270 on the 360. Don't want to fiddle with the jetting. Anybody give me an idea as to what they are running
Barry
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I run 20:1, using Castrol R30, in my MX250 and I used the same plug for 4 meetings without fail.
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I run 20:1, using Castrol R30, in my MX250 and I used the same plug for 4 meetings without fail.
You using standard jetting, and where were you on sunday!!lol
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Standard jetting all round, and I was standing outside my house waiting to get picked up by my mate Marc so we could be flaggies but he was crook and didn't let me know until it was too late to get down in time (not that I could afford to drive that far by myself anyway).
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when it fouls the plug, is it by any chance when the revs drop back onto the idle circiut?
if so, i had the same problem with my 125 and traced it back to the pilot being too rich.
most of the earlier Yammies were too rich on the pilot anyway.
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when it fouls the plug, is it by any chance when the revs drop back onto the idle circiut?
if so, i had the same problem with my 125 and traced it back to the pilot being too rich.
most of the earlier Yammies were too rich on the pilot anyway.
No what you're talking about,but no not that problem, cheers
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Try running synthetic at 40:1 like they recommend, modern oils are not meant to be run at 25:1.
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have a good read here
http://ozvmx.com/community/index.php?topic=2533.0
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Why not read the article in the latest VMX mag about 2 stroke oils from Sean Phillips of Belray Australia. I think he might know what he's talking about.
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have a good read here
I read the link and understand it.
So what are people running in there MX250 and did they have to change the jetting
The problem I have in my head is that if I go to synthetic and the quote 40:1 is what everyone says. but I am told I will need to change my jetting, I am also aware that some synthetics are better than others. I realised that I have made a mistake running synthetic at 25:1, though it appears about correct for mineral based oils.. Think i'll start with the good old Catrol R at 25:1 and see where we go, or should i say if we go
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This was from a set of specifications given Latest VMX had good article on oil choices suggesting 40:1 on synthetic
Yeah read that thread
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Just because its in VMX mag doesnt mean its right. Remember Belray were one of the main instigators and pushers of 50 to 1 and lean ratios back then ;)
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Just because its in VMX mag doesnt mean its right. Remember Belray were one of the main instigators and pushers of 50 to 1 and lean ratios back then ;)
good point, should I also change plugs as using B9ES at moment
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my manual states B8EV for the MX250a {mine is using a B8ES},
i use shell advance sx 2 stroke oil at around 23:1 with no probs.
but then again, my MX250 only has about 10~15 minutes of ride time on it since its rebuild so i'm still yet to fully see how it runs. CD6 will be my test for that bike.
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Just because its in VMX mag doesnt mean its right. Remember Belray were one of the main instigators and pushers of 50 to 1 and lean ratios back then ;)
Are you saying the rep from a major oil company doesn't know what he's talking about??
Ha..I've heard it all now
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I've been running Motul M800 at 20:1 in my Yamaha 125s + DT1, and have no dramas with fouling plugs. Not all of them are jetted all that well either...
Certainly no dramas with wearing stuff out, or blow-ups either.
I was always a bit of a fence sitter WRT the ratio debate. The Lozza pointed out that ALL of the reasons for lean oil:fuel ratios were about convinence and cost, and NONE of them were about performance or longevity. I jumped on board the 20:1 boat, and haven't had a moment's regret. Also worth noting that the leaner your oil:fuel mix is, the greater the consequences will be if you make a slight miscalculation when mixing... ;)
Generally speaking, the larger the engine, the lower it will rev - so the leaner you can safely run the oil mix.
What brand of fuel are you using? The 98 octane Shell fuels have a known tendency to foul plugs in carb'd engines - something to do with trailing throttle/idle, and the way the EFI cuts the fuel right back in those conditions (carbies do not).
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I've run Motul 800 at 40:1 in all my bikes with no problems, any more oil than that and it spits out everywhere. What Lozza says is the opposite to what Mr Belray says.. who do you believe? I think i'll go with the guy that gets paid to know and promote oils. I run BP ultimate fuel and have had great results.
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I've run Motul 800 at 40:1 in all my bikes with no problems, any more oil than that and it spits out everywhere. What Lozza says is the opposite to what Mr Belray says.. who do you believe? I think i'll go with the guy that gets paid to know and promote oils. I run BP ultimate fuel and have had great results.
I've been using the 98 Octane Caltex petrol, simply because its the only 98 octane available local to me. I have no complaints with it.
When Mr BelRay can tell me (over the phone) how to port an otherwise standard DT1 so that it is consistantly 3rd or 4th into the first corner against the pre-70 big guns, then I'll listen to him over Uncle Loz. ;)... :D
Like I said, the thing that convinced me was that all of the arguments for lean oil ratios were for things like "low carbon build up", "less smoke", "less money spent on oil" and the like.
None of which has any relevance to an MX bike, at least not when compared to "maximum power" and "doesn't go boom".
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I spent a day at the farm earlier in the year with my old square barrel, my ex '81 490 my mates IT465 and another mates '02 360 Husky. In the past I always use Castrol TTS @30:1 with no problems but had changed to Motul @ 40:1 in recent times because that's what my mates were using. All of the other bikes used Motul except my mate with the IT who used Silkolene @40:1 (because he got 10 litres of it for free!). Anyway, we decided to do some chopping and changing of petrol/oil ratios and plug chops to see what was going on within. In the end, I found that my bike ran a little nicer with BP 98 fuel and Motul @30:1 and most of the more modern bikes were happy on Motul 40:1.
I'm not one to experiment too much after an early seventies disaster using some evil stuff called Gary Jones Racing Oil that seperated in the fuel and blew up three of our Maicos at Woodstock short circuit. It'd been reccomended by Maico importer Blair Harley who coincidentally imported the shite. He didn't tell us we had to keep shaking the can to keep it suspended in the fuel. It was safe old Castrol TT and later TTS after that. It now appears that Motul is the oil of choice so I'll stick to my 30:1.
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I use Motul 800 at 35:1 and never had a problem.
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i am with johhny o and dj :-*
i have run motul 800 at 40 to 1
in everything from pre75 to pre78 evo
up to modern never a problem
never change my plugs
it can be run down at 30 to 1 with no problem as well
must use bp ultimate at all times ;)
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i am with johhny o and dj :-*
i have run motul 800 at 40 to 1
in everything from pre75 to pre78 evo
up to modern never a problem
never change my plugs
it can be run down at 30 to 1 with no problem as well
must use bp ultimate at all times ;)
Yes the old BP ultimate 98 and I aslo mix it 50/50 with avgas. The other guys I ride with mix Motul 800 at 32:1 and we will share the fuel and I havnt had a problem with fouling at 32:1 on up to 40:1
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I'll run anything I can get from K-Mart or Big-W that is 2 stroke racing oil, and mix it at 40:1 . I run B8eS plugs. Haven't looked at the carburetor yet. I would rather leave that tuning stuff to the professionals.
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ok, yeah, I always just try and buy 98 octane BP as a rule.
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i dont think its got anything to do with your oil, il'd say either your not running on the pipe, your spark plugs are a shit batch, or most likely your coil or electrics are weak, i have had the same plugs in both my MX250a, 360a for 3 season's and there still the same NGK plugs in there.
THe jetting numbers seam a bit light if anything to me i think im on 270 and 300 respectively, so id say if its oil fouling start looking at you plug and the power getting to it, maybe the black box or the coil is shite,
its an A model right , not the 73 model ?
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i dont think its got anything to do with your oil, il'd say either your not running on the pipe, your spark plugs are a shit batch, or most likely your coil or electrics are weak, i have had the same plugs in both my MX250a, 360a for 3 season's and there still the same NGK plugs in there.
THe jetting numbers seam a bit light if anything to me i think im on 270 and 300 respectively, so id say if its oil fouling start looking at you plug and the power getting to it, maybe the black box or the coil is shite,
its an A model right , not the 73 model ?
Running both the 360 and 250 on the standard jetting. Ran the 360 all last season with very few probs. But been doing plugs on it this season after changing oil The 250 will run great on the pipe for first lap and then start 4 stroking or loading up. Went through three plugs at last meeting.
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The 250 will run great on the pipe for first lap and then start 4 stroking or loading up. Went through three plugs at last meeting.
You have a prob - that aint normal :o. Four stroking and loading up suggests carb although it could be a compound prob.
Unless of course someone slipped in a Bully motor when you weren't looking ::) ;D.
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You have a prob - that aint normal :o. Four stroking and loading up suggests carb although it could be a compound prob.
Unless of course someone slipped in a Bully motor when you weren't looking ::) ;D.
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Now I'm starting to worry, think I'll get the electrics checked out
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I wouldnt worry it can only be 2 things petrol or spark.
YOU have an issue, what you describe isnt right.
MY money is on the spark it might be failing away after the bike gets warmed up, and as its breaking down its struggling to keep the oil alight, can you try a new coil ? At $20 its a cheap way to check.
IF i Motorcross a 360 and over rev it like on the line or overrun oin the straight, it can kill a plug , in my case i searioulsy think its somthing in the way it advances and spikes out the plug, but im prity sure its not carby related as i can leave it on the pipe in the DT frame and never misses a beat.
IF you have clean jets and pilots, my suggestion is go down the hot path, when it gets hot your getting a breakdown in there sowhere, put you 360 electrics on the 250, and see what happens when it get up to temp, still does it, also try swapping over the stator plates, if it still does it and you have ALL the known working electics on it, then report back.
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before you do anything check that your drive side crankcase seal is not leaking.i had 1 blow off on a 360 once and the motor still ran but oild up plugs.the best way to check is to drain the oil from the motor and check how much came out.if real low you can say 1 seal is gone 2 (poor mainance)
anyway buy some castrol r30 2t oil fill the gearbox with the corect amount of oil.start motor run for a while,with the motor runing smell exhurst.r30 has its own smell and if you can smell the r30 burning you have a brown drive side seal,as the only way it can get in the engine is through the drive side seal.
if blown change both seals
good luck
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Hey Tossa, at the next race meeting have a go on my MX250 it's PVL equipped. If things go to form I will probably be too knackered for the "all in" last race so you can see how my MX compares to yours.
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Hey Tossa, at the next race meeting have a go on my MX250 it's PVL equipped. If things go to form I will probably be too knackered for the "all in" last race so you can see how my MX compares to yours.
cheeky bugger, thanks Marc will definitely like a look
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It's MICK!!!!! Marc's the guy on the Honda XL250 #212 ;D
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It's MICK!!!!! Marc's the guy on the Honda XL250 #212 ;D
Oops, old timers setting in, sorry. Riding the 250 at this point at Manji, got problem with gear selector that's being looked at as well as the fuel problem. If i can't fix it in time will take the 360 and try not to kill myself!!lol
Barry
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GEar selector ?
IF its pooping out ( usually second) check the shift drum its probally got a rounded worm on 2nd /3rd and then if you look at the 2nd/3rd gear it will have rounded dogs usually on both where it locks the inners
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Barry - just going through the same exercise with my 360B. Runs well now on the pipe (360 Main although Rod Gilchrist is on a 400) - but is dirty until half way down the straight - as someone mentioned earlier maybe too rich on the pilot. I run Silkolene at 40:1 tried Motul but appeared to smoke more than the Silkolene. Did my first NGK plug in 5 years at the weekend - B9EGV.
cheers
Rossco - #34
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GEar selector ?
IF its pooping out ( usually second) check the shift drum its probally got a rounded worm on 2nd /3rd and then if you look at the 2nd/3rd gear it will have rounded dogs usually on both where it locks the inners
yep in the right area, going up through the gears no worries, diving into a corner in 3rd and down into 2nd end up in nuetral, exciting not!!!
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Barry - just going through the same exercise with my 360B. Runs well now on the pipe (360 Main although Rod Gilchrist is on a 400) - but is dirty until half way down the straight - as someone mentioned earlier maybe too rich on the pilot. I run Silkolene at 40:1 tried Motul but appeared to smoke more than the Silkolene. Did my first NGK plug in 5 years at the weekend - B9EGV.
cheers
Rossco - #34
hear where your coming from, this has opened my eyes to the number of variances that people use in fuel mixtures and jetting. The newer types of oil and the old jetting sometimes just don't work. But the answers given by people can also confuse. So have picked a way to go and hope that it doesn't end up in a hole at manjimup. Hold on that won't even matter will end up in a hole anyway!!lol
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When I read that article in the last VMX mag about oil recommendations written by that Bel-Ray guy I was going to withdraw my subscription and write a letter of complaint to the VMX editor in how they can publish such important information from ONE source that is in whole INACCURATE and will be the cause of potentially hundreds of stuffed engines in the VMX scene if riders take that advice..
Lees oil is a disaster!