121
Suzuki / DR400 fork dia
« on: September 07, 2008, 09:30:24 AM »
Gents,
Does anyone know the forktube dia for 80/81 DR400?
36mm?? 38mm??
Thanks
Does anyone know the forktube dia for 80/81 DR400?
36mm?? 38mm??
Thanks
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122
General Discussion / Terry Pratt on 72 GP250 season
« on: September 03, 2008, 12:34:59 PM »
Does anybody know if Terry Pratt's book on the 72 250GP season is available in OZ?
123
Maico / Maico 326 revisited
« on: August 23, 2008, 11:27:23 AM »
Gents,
Just revisiting this topic after catching up on back-reading on page 5.
Have any of you followed thro on building one? Mention was made of using a 400 sleeve/barrell, but the 400 engine had 13mm longer stroke. (83 vs 70mm) I would have tho't that would cause major problems in using a 400 barrell or sleeve on a 250 bottom end.
I would have tho't it better to make a new liner to suit the 400 piston (77mm) & 250 stroke. I recently measured a 250's cases & it seems the cutout in the cases for the cylinder spigot is sufficient to take a 400-size sleeve, but not sufficent to take a sleeve made for an 80mm Yam 360 piston w'out machining (which would give 351cc).
Another possibility is to adapt a Yam top-end, something I wanted to do back in the day (as mentioned in another post), but never had the resources.
Mention was made of the Maico at CD2 featured in VMX. I talked to him/them at CD5 & by then he/they had 2 modified 250s. He was a little guarded w his info, but it seemed both had specially made sleeves, one to take a 77mm 400 Maico piston, & the other to take an 80mm Yam 360 piston.
Does anybody on the forum know more about those bikes?
PS. Mark, I think the SA racer who built/raced a 326 was Geoff Flink wasn't it?
Just revisiting this topic after catching up on back-reading on page 5.
Have any of you followed thro on building one? Mention was made of using a 400 sleeve/barrell, but the 400 engine had 13mm longer stroke. (83 vs 70mm) I would have tho't that would cause major problems in using a 400 barrell or sleeve on a 250 bottom end.
I would have tho't it better to make a new liner to suit the 400 piston (77mm) & 250 stroke. I recently measured a 250's cases & it seems the cutout in the cases for the cylinder spigot is sufficient to take a 400-size sleeve, but not sufficent to take a sleeve made for an 80mm Yam 360 piston w'out machining (which would give 351cc).
Another possibility is to adapt a Yam top-end, something I wanted to do back in the day (as mentioned in another post), but never had the resources.
Mention was made of the Maico at CD2 featured in VMX. I talked to him/them at CD5 & by then he/they had 2 modified 250s. He was a little guarded w his info, but it seemed both had specially made sleeves, one to take a 77mm 400 Maico piston, & the other to take an 80mm Yam 360 piston.
Does anybody on the forum know more about those bikes?
PS. Mark, I think the SA racer who built/raced a 326 was Geoff Flink wasn't it?
124
Maico / The humble 250 Maico
« on: August 19, 2008, 11:57:29 AM »
Just following up on some comments on the humble 70s 250 Maico in other posts.
No doubt a VR, Phantom, Pursang, 'snore etc would out-drag it, but they weren't too far off the pace. I do recall that I often got holeshots on my 73 bike in 74 as did other maico pilots in the region, but we weren't national calibre.
In Oct 75, DirtBike printed a copy of the factory modification bulletin recommending porting changes to Ex & Inlet. Ex to be 37mm from top of liner, 58mm wide at top (above transfers) & 52mm wide at bottom. Inlet to be 113mm from top of liner & 52mm wide. Barrels stamped later than June 75 were said to have these specs.
I recently measured 2 barrells from 73 & 74 & both were almost exactly that in heights (didn't check widths), but I don't know if they were stock or not (didn't look all that closely at the time). Transfers were 52mm from top of liner.
That translates to Ex opening about 86.5deg ATDC & transfers opening at about 113deg ATDC for durations of 187deg & 134deg respectively, both of which are rather radical/advanced. Bridged Ex & transfer ports (4 of, plus boost port) are rather large, taking advantage of the benefits of a long-stroke motor. Whether you go on total duration or time-area they're rather hot specs.
So why were they off the pace at the poity end?
Lozza says he gets better performance out of unbridged exhausts & I don't doubt him, but lets stick w the bridged port.
I suggest 1) heavy flywheels consume horsepower to spin & to accelarate, & 2) perhaps the main reason, the inlet duration is only about 160deg (w an 80mm piston skirt which I think was std). Not only that but the sizeable boost port tookup some of the inlet port area, so on both duration & time-area the inlet is very mild (which was typical of euro thinking of the day, tho there were some exceptions)
DirtBike claimed the factory experimented w lighter flywheels on the 250 but never went into prod'n w them.
Seems to me that if you want a faster 250 Maico, start on the inlet area/duration, & if yr real serious, turn some weight off the flywheels.
Anyone tried it?
A friend of mine on a very quick 'snore says he was zapped by a 250 Maico at the Dirttrack nats like he was standing still. No doubt there are some quick ones out there.
Anyone got any other tips that aren't top secret?
Mark, you said in another post that yr flouro-orange one was quick. Do you recall what was done to it?
No doubt a VR, Phantom, Pursang, 'snore etc would out-drag it, but they weren't too far off the pace. I do recall that I often got holeshots on my 73 bike in 74 as did other maico pilots in the region, but we weren't national calibre.
In Oct 75, DirtBike printed a copy of the factory modification bulletin recommending porting changes to Ex & Inlet. Ex to be 37mm from top of liner, 58mm wide at top (above transfers) & 52mm wide at bottom. Inlet to be 113mm from top of liner & 52mm wide. Barrels stamped later than June 75 were said to have these specs.
I recently measured 2 barrells from 73 & 74 & both were almost exactly that in heights (didn't check widths), but I don't know if they were stock or not (didn't look all that closely at the time). Transfers were 52mm from top of liner.
That translates to Ex opening about 86.5deg ATDC & transfers opening at about 113deg ATDC for durations of 187deg & 134deg respectively, both of which are rather radical/advanced. Bridged Ex & transfer ports (4 of, plus boost port) are rather large, taking advantage of the benefits of a long-stroke motor. Whether you go on total duration or time-area they're rather hot specs.
So why were they off the pace at the poity end?
Lozza says he gets better performance out of unbridged exhausts & I don't doubt him, but lets stick w the bridged port.
I suggest 1) heavy flywheels consume horsepower to spin & to accelarate, & 2) perhaps the main reason, the inlet duration is only about 160deg (w an 80mm piston skirt which I think was std). Not only that but the sizeable boost port tookup some of the inlet port area, so on both duration & time-area the inlet is very mild (which was typical of euro thinking of the day, tho there were some exceptions)
DirtBike claimed the factory experimented w lighter flywheels on the 250 but never went into prod'n w them.
Seems to me that if you want a faster 250 Maico, start on the inlet area/duration, & if yr real serious, turn some weight off the flywheels.
Anyone tried it?
A friend of mine on a very quick 'snore says he was zapped by a 250 Maico at the Dirttrack nats like he was standing still. No doubt there are some quick ones out there.
Anyone got any other tips that aren't top secret?
Mark, you said in another post that yr flouro-orange one was quick. Do you recall what was done to it?
125
CZ / 125MX engine
« on: August 19, 2008, 10:56:54 AM »
Do any of you CZ gurus know the 125MX engine?
Was the barrell a 250 barrell w a super think liner & milled down in height for the shorter stroke? (like GE claimed in a 90's ADB article on VMX 125s)
Was the barrell a 250 barrell w a super think liner & milled down in height for the shorter stroke? (like GE claimed in a 90's ADB article on VMX 125s)
126
Honda / XL500/250S cams
« on: August 14, 2008, 05:38:19 PM »
Can anybody tell me if the cam in XL500S interchanges w XL250S like the early 70's XL350 cam was interchangeable w XL250 motosport?
Thanks
Thanks
127
Wanted / Classic Dirt Bike magazines
« on: August 07, 2008, 10:42:00 AM »
Does anybody have any issues of Classic Dirt Bike mag that they'd be willing to part with?
Thanks
Thanks
128
Yamaha / YZ125/IT200 tanks
« on: August 06, 2008, 06:36:47 PM »
Hi Guys
Can anyone tell me if YZ125K/L/N tank will fit IT200L/N?
Thanks
Can anyone tell me if YZ125K/L/N tank will fit IT200L/N?
Thanks
129
Wanted / 76 TS185A engine/parts
« on: July 30, 2008, 10:34:20 AM »
Hi all,
Has anyone got a spare 76 TS185A engine? Or any engine parts? Bottom end? Ign parts? (other TS185 ign parts would suit I think).
thanks
Has anyone got a spare 76 TS185A engine? Or any engine parts? Bottom end? Ign parts? (other TS185 ign parts would suit I think).
thanks
130
Other Makes (CanAms, Coopers, etc) / Canam MX2/TNT seat-foam & cover
« on: July 26, 2008, 06:15:30 PM »
Can anyone tell me if the MX2 seat-foam & seat cover are the same shape & size as TNT of same vintage (75)?
131
Honda / Honda model ID
« on: July 21, 2008, 12:41:33 PM »
Gents,
There used to be a good honda model ID & specs on 100megsfree4.com
I believe its been shifted to a new address/site but I can't find it. Does anybody know the new address/site? (I've had no success googling it)
There used to be a good honda model ID & specs on 100megsfree4.com
I believe its been shifted to a new address/site but I can't find it. Does anybody know the new address/site? (I've had no success googling it)
132
Suzuki / DR400 (twinshock) magazine test
« on: July 18, 2008, 08:25:25 AM »
Does anybody have any magazine tests of the DR400 (circa 1980) that they could scan for me?
133
Suzuki / SP370-DR400 cam interchangeability
« on: July 17, 2008, 12:23:49 PM »
Can anyone tell me if the cams are interchangeable on the 370 & 400 SP/DR's of late 70's-early 80's?
134
Suzuki / SP/DR 370/400 engine weight
« on: July 14, 2008, 06:05:44 PM »
Hi Guys
Does anybody know the weight of an SP370 or DR400 engine?
Does anybody know the weight of an SP370 or DR400 engine?
135
General Discussion / New "Marque Remark" category?
« on: July 06, 2008, 02:38:19 PM »
Gents,
Just looking thro the "Marque Remarks" one can't help noticing there's nothing there for Canam & Cooper.
Bearing in mind the impetous such a forum as this gives to the restoration & preservation of different marques, esp if there's a marque-specific category, I was wondering if it was worth asking "Admin" to initiate another category specifically for Canams & Coopers.
Might even get a bit of Jones-Islo/Ammex & Carabela thrown in from US guys. Perhaps even HD MXers could be included. (I'm sure many of you would have seen the highly desireable one at CD)
What you think?
Just looking thro the "Marque Remarks" one can't help noticing there's nothing there for Canam & Cooper.
Bearing in mind the impetous such a forum as this gives to the restoration & preservation of different marques, esp if there's a marque-specific category, I was wondering if it was worth asking "Admin" to initiate another category specifically for Canams & Coopers.
Might even get a bit of Jones-Islo/Ammex & Carabela thrown in from US guys. Perhaps even HD MXers could be included. (I'm sure many of you would have seen the highly desireable one at CD)
What you think?