GM frontera

[searbs]

Lyle,
if your still chasing a pipe for your mk11, there's one here and lots of other stuff too
John


http://cgi.ebay.com/ebaymotors/1979-bultaco-frontera-mk-II-250-pipe-muffler-exhaust_W0QQcmdZViewItemQQ_trkparmsZ72Q3a1208Q7c66Q3a2Q7c65Q3a12Q7c39Q3a1Q7c240Q3a1318QQ_trksidZp3286Q2ec0Q2em14QQhashZitem330283968807QQitemZ330283968807QQptZMotorcyclesQ5fPartsQ5fAccessories

[JC]

There has been some misinformation here.

As I understand it, Mk 9 250/370 Fronteras (M152/143) were based on MK8 125/250/370 (M144/135/136) Pursang frame & swingarm.

MK10 250 Frontera (M180) was based on Mk9 125 Pursang frame, forks & swingarm, but diff sidecovers around airbox. (Maybe diff airbox too to make room for the battery)
MK10 370 Frontera (M181) was based on Mk9 250/370 (M167/168) frame & 38mm forks but MK10 style swingarm

My Gold Medal 250 Frontera was clearly a MK10 250/370 Pursang frame, swingarm & 35mm Mk10 Pursang forks but the frame was stamped w 180 prefix even tho it clearly was NOT based on the Mk9 125 Pursang frame. My GM engine # was 492 prefix as I believe they all were. As I recall airbox & sidecovers were straight MK10 250 pursang.

[lyle2212]

Yeah I noticed that mk11 pipe on ebay,unfortunately it,s for a 250cc (m214) and I,m after the 370c(m215). There is one on ebay in spain ,though it,s a bit dinged up..... I rang the ol' mate from vintage dirt who is putting my mk11 seat together, and he can make me up an air box as he has the same gm frontera. ...I believe that VMX edition 20 or 21 has the info on the gm frontera and how they came to be, if memory serves me correctly they were indeed a batch of mk10 pursangs destined for the  USA, but they had production delays, so to keep the peace with the buyer they made a few changes to them and thats how they came to be an enduro rather than motocross bike.

[lms6201]

jc  ,u could be right on the 180 relationship with the mk 9 125 ,instead of the mk8, i definatly see one of them in my bike (180)dony has told me if i fit a mk7 swingarm it can be used in pre 75 , but he may think i have the mk9 frntera ,  as u can see the rest of my post agrees  , the pursang mk10 with comp plate (aka gm ) frame in the shed is begging for a powerplant  , actually both my 180 and 181 are in the pic from conandale vinduro close to the control building , red and blue

[JC]

Ims,

Yes I'm certain that the Mk10 Frontera 250 M180 frame is based on Mk9 125 pursang frame. I have it stated in the Mags of the day & I have such a frame in the shed & clearly its not Mk8 pursang & wouldn't be legal for pre75 w a Mk7 swingarm. The top shock mount is a lot further forward & seat frame-loop is diferent to Mk8 Pursang. Airbox covers different also

The GM 250 Frontera frames stamped #180 prefix (as mine was) is straight MK10 Pursang 250/370 - not even extra brakets for bashplate or centre-stand. Bashplate wouldn't have fit anyway as pipe was straight pursang pipe (w extra muffler attached to tip) which is quite a diff shape (esp under the engine) to Frontera pipe.

Is yr Mk10 frame w comp plate stamped 180 prefix or 492/493? 

I think there may have been 2 batches of GM Fronteras w frames stamped different prefixs.

[lms6201]

mine,s stamped 180 and is dated 1978   ,i have the extra silencer on the mk10 frontera ,  thanks for the info on the 180 frame , donny must have mixed it up with a mk 9 ,  and it looks so much different from my mk 7 pursang 

[Bullymad]

The difference with the 250 Pursang/ Frontera frame thing is the width.
One may be a extract from the other but the fronty is wider in the airbox/seat area, thats why the Pursang airbox doesn't fit.
Floody told me that the only reason the GM came here was because when he was in spain at the factory he saw the first shipment
that was going to the US.
He told Bulto that he wanted some so they shortchanged the yanks and limited no's came here.
The original GM was created by 2 brothers Bultaco sponsered in California from a Frontera frame and a Pursang motor to compete in the six day.
They painted it gold because they were confident of winning the gold medal.
The bike did very well so the factory introduced it as a new model.
Some Australian bikes were supplied with Preston Petty bits.
The silencer on the pipe was due to pollution laws in the US