Mine was built in the old days, but bad welding screwed it & its been suffering as I dragged it out over a decade later & tried to get it raceable on no money. The YZ piston with MB rod was not a good idea.
No8 Wire Extraordinaire
Mine was built in the old days, but bad welding screwed it & its been suffering as I dragged it out over a decade later & tried to get it raceable on no money. The YZ piston with MB rod was not a good idea.
Don't you look at my accountant.
He's the only one I've got.
Forum whore
what went wrong with the rg150 turned to a 100? thought that was a good idea?Originally Posted by F5 Dave
No8 Wire Extraordinaire
That was aircooled RGV150 into 125.
Same problem. Conrod was wrong size for piston. By the time someone had pressed the pin off centre into the crank & I had to get it redone & welded that was that crank's fate sealed. the small end bearing that mates the two together was less than up to the task & it fell apart, twice.
Was time to bail out rather than find another RGV engine & start again. Decided I wanted a 100 & my MB motor was still there. Maybe I could get it going . . . .
Heck it showed its promise, - built on rubbish foundation, that's all.
Don't you look at my accountant.
He's the only one I've got.
Forum whore
I was thinking the same thing this afternoon. I don't remember Jimmy and Ken Steadmans, Steve Diproses (Rams old bike), David Diproses or Chris Pickets bikes (and others I can't name atm) blowing up enough to say there were unreliable. All of them had atleast 20 hp except for Pickets RG50. Hell my KERG (25hp) finished the Ohakea GP, a visit to Manfield and Ohakune, several Taupos and numerous Mt Welli meets on the same motor and not one blow up.
I don't think the apparent unreliability of the current 2 strokes can be totally put down to all the HP they have 'found' causing extra stress on the motors. A good platform, design, engineering, careful (and smart) assembly and proper maintainance (and SOME cash) has a lot to do with consistantly finishing races at or near the pointy end.
Just my opinion and in my opinion it is the correct opinion...
Forum whore
just like the side cars having to carry two people around alot heaver. lm shore mine put out some good hp and only dnf one out of 5 gp's l went in. l think if alot of guys just backed off 3 - 4 hp a bit of retard a bit risher a bit less piston to head cearance they would finsh ok and still have a fast bike./ some good engineering like you said is realy needed
No8 Wire Extraordinaire
Hey my bike had just that morning been fed another mainjet up from totally safe & retarded another couple of degrees as a precautionary measure.
Crankcases that leak from bad & copious welding + running a YZ 16mm piston to a rod with 14mm se just were a bad base to start from. We all knew that, but two v.young kids, down to one income, & a recession & a garage of bikes to feed & there isn't enough to go around.
So I'm selling a bike to generate some funds & start again. As I said I machined the cases at Christmas. The welding is done, just need to devcon & do the sidecovers, then populate a bunch of bearings & decide on how best to destroke the crank.
oh yeah & remount engine with new mounts & repair damage to current barrel, or start another.
Don't you look at my accountant.
He's the only one I've got.
Forum whore
l know what your saying and are in the same boat my self athritis dose not help at all . also make it very hard to race having more bad days than good but would love to get a race in at some stage.
No8 Wire Extraordinaire
Easter would have been an ideal low pressure environment. there's two corners you have to brake hard for though, not sure if that is an issue.
Don't you look at my accountant.
He's the only one I've got.
Anorak
Oh I was actually thinking the same thing too, but i believe the quality of competition is higher.
The quality of the parts has not improved and if anything it has decreased.
Think about it for a minute where a lot of the parts are being made now, margins are tight and in real terms the parts are now actually cheaper than they used to be. So there will be inevitable compromises.
Even Dave's Genuine Yamaha YZ100 piston's which were made say 30 years ago would not are got better with age.
Think how many times they would have fallen off the many shelves they would have inhabited.
If then you add all the above with the fact that the difference's in stress between say 20 to 25hp or 25-30 hp with similar parts is huge, possibly 2x the stress.
Hp is indeed costly, as are cutting corners.
But yeah correct choice of parts coupled with clever attention to detail and calculated assembly of often rewarded in all forms of motorsport.
To finish first first..... well you all know the rest.
Oh yeah Dave talk to Kel re the rods he has the list he is working on at the moment.
Plus i may have found one last night as well. Legal to in my opinion. But i will throw it open to the panel first.
Kinky is using a feather. Perverted is using the whole chicken
Forum whore
the breaking would be the hardest .think l need to build a bike with high bars on it to take the presser away from my arms . l shame breaking was one of my strong points after you said you could out break me easy years ago lol l put that down to my success in the f3 racing. is there a meeting this weekend there?
Bucket Racer/Crasher
The other option you have Dave is to go for a rod with a 24mm pin and bore the pin holes out on the crank offset 2mm which will result in a 4mm increase in stroke. With a KT100 piston it will start out at 113.7cc. ProX have a 115mm long rod which is 15mm wide with a 24mm pin - 03.6610. KT100 pistons are about 7mm shorter pin-crown that an MB piston. Good quality BE bearings are available as well
Anorak
As you seem to have used ProX stuff Mike how do the prices work out?
Kinky is using a feather. Perverted is using the whole chicken
Forum whore
would a 1978-82 cr125 56mm piston be any good?
Unknown Disorder
pretty sure there is
No8 Wire Extraordinaire
That is what DC in chch used. Nah I want to build a 100, thanks anyway.
Don't you look at my accountant.
He's the only one I've got.
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