OzVMX Forum
Clubroom => General Discussion => Topic started by: fatboyracing on September 24, 2011, 07:53:09 pm
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Question for everyone,
Will a xl350 honda motor fit into a bultaco 250 1974 sherpra frame I would like to try this mod ,has anyone tried this ? I am about to purchase a sherpia bike and I have heaps of xl motors. The forks are the same size as honda and shocks are the same length the big difference is the frame weight I recond it will be 30 kg lighter then standard XL when finished. The light weight chrome olly frame will make a big difference to the over all riderbility (if there is such a word) I hope you guys can help or maybe give me some suggestions
cheers
Fatboy
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I think you'll have the spanish mafia putting a price on your head if you do, saw a sherpa fitted with a motorsport motor in a cockies shed years ago
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There's an XL350-powered Bully running in WA, the South African rider Rob Wickes rode it up front at Narrogin at the 15th Anniversary meeting. It's owned by Mark Thomas : from (admittedly ravaged) memory, the lower frame rails had minor mods, but it was otherwise a relatively straightforward insertion.
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Believe there are pics of it on the 15th Anniversary topic on vmxwa site.
It hammers along too !! :P
cheers S&A WA
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There was couple of XL powered Pursangs racing in NSW and Qld a few years ago. If the swap is anything like fiting an XL to a Montesa or CZ it'll be a nightmare. Not sure about the Sherpa frame though Shane.
Are you building a motocrosser or trials bike? The steering geometry of the Sherpa might be a little squirilly for MX but it might work OK for dirt track.
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http://www.avcmc.iinet.net.au/201104/xl350.html
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Thanks guys for the info looks maybe not too bad of a project I will take lots of picts for everyone to see how it goes.
I am going to start today by taking some measurements to see how tight the motor will be.
The steering stem is a lot more layed down then orginal xl I hope this will make it turn alot easier then original
The back brake pedal will be a challenge
I dont no how it will handle on the MX track Mark but hopefully it will be alot lighter and will turn more like a MX bike then a road bike.
Cheers
Fatboy
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Don't like being a stick in the mud fatboy but that bulonda that davy posted has a 74' pursang frame, owning both a pursang and sherpa believe me the sherpa frame/swingarm is nowhere near as strongly built as the pursang, id be a bit skeptical if it would handle that motor :-\
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Just had a measure up of the frame swingarm etc I think that Huskibul is right the swing arm is pretty light weight for MX so I have also got a Pursang swing arm that is a lot stronger and longer and should fit with a small spacers on each side. The motor should fit in to the frame ok. But I will wait until I pick up the frame next week to measure the motor properly.It is very light chrome olly frame abit like a push bike compared to a XL
cheers
Fatboy
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yastill won't beat the YZ FB~!!! But keep on trying ;D
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Fatboy, I could be wrong, but a 74 sherpa might only have a steel frame not chromemoly. (Pursangs from 74 on had chromemoly).
Feetup Dave would probly know.
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The Sherpaframes often crack at the steeringhead with original engine in trials riding. It's flexy and weak. I'd only imagine what it will be like with a honda 4 stroker on a mx track. :o
I also think it's regular steel.
If you're going to put in all the work of building a special i think you'd be better off getting a Pursang frame to start with.
For mx use that is, if you're building a trialsbike you're on the right way.
Whatever you do, put up pics.... :)
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XL259 with 305 big bore might be better fit and power?
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There are loads of mid 1970s Alpina frames that noone wants that have a frame that is lightweight (especially compared with a Honda XL350 frame) and the same main frame geometry as the Sherpa T but they have more frame elements around the mid section which make them more robust. The riding stability they enjoy over the Sherpa T is due to having a longer swingarm and Pursang/Frontera triple clamps (more trail).
I'm talking about Alpina models 116/117 and 137/138. which were made 1974 -1976.
I suspect a Sherpa T frame would fall to bits pretty fast with an XL350 motor in it unless it was only used on smooth roads. Sherpa Ts are probably the most flimsy of the mid 1970s trials bike frames, especially the front downtube/top tube/steering head area.
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Sounds like I maybe barking up the Wrong tree, sounds like I might need a pursang frame They are hard to find in tassie. I know nothing about bultaco's steel, chrome olly etc but I am listerning to you guys any one go any more suggestions? I have about 5 complete 350 motors no 250s and would really like to make a special.
cheers
Fatboy
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I still can't work out if you want to make a trials special or a racing special
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I may have access to an Alpina frame but they have all the battery box etc which I spose could be removed Are they the enduro 350 model ? Is the Alpina frame steel or chrome olly?
Cheers
fatboy
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I want to make a light weight MX bike.
I have been racing an XL for 10 years or so and have enjoyed it but now I need to lighten down the bike or the rider and the only way I can lighten down the rider is to cut off a leg.
Do you think an Alpina frame would be much lighter and would it turn any better then a XL
cheers
Fatboy
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Just Chucking one out there,
what about a custom frame made ,may be a job for GMC to your specs
May be a bit more dollars but could save alot of time trying to find a good frame match, and trying to make it handle and steer etc.
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The best turning MX bike I have ever ridden had a bombed 370cc XL250-based motor running on alcohol fitted in a pre-75 Maico frame.
I think the XL350 motor design is too heavy to ever be in the same class for handling as an XL250-based motor, no matter what frame it gets fitted into.
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Shane how about a lowered DT1 frame with a RT swing arm 1" longer and Honda 350. hondaha!!!
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now I am even more confused, I dont think there would be many pre 75 Maico frames for sale I think I really need a rethink. I thank everyone for there answers I am still looking for the best options
Cheers
Fatboy
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buy a YZ B :D
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I'd echo all the skeptical comments about putting it in an Alpina frame.
The geometry is all wrong for MX, not to mention weight distribution. It'd be awfully front-end heavy, esp if you used a longer swingarm (to get a decent length wheelbase).
And the engine bay is not very deep, esp below the pivot, where the honda engine requires it.
I have seen it done, & it was ridden in a VMX meet at Proserpine, but not very successfully.
The 115/116 Alpina frames are steel. The 137/138 frames are chro-mo & are VERY fragile, even with the extra bracing they have. I have a couple of 138 frames which are cracked & gussetted everywhere (eg downtube, backbone, rear shock mounts), just from trail use w the Bul engine which is much lighter than the XL engine
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I've seen Honda 4 strokes in nearly every pre '75 frame imaginable and nearly all of them have been less than successful, each for its own reasons. I personally have used Montesa King Scorpion frame...(too heavy and the bottom frame rails need to be lowered to get the sprocket as close to swingarm centre as possible) and CZ (Same work as the Monty although much lighter). As good handling as the Maico is, it's not the ideal candidate either although the engine does fit a lot neater than most. The major problem being exhaust clearance with the twin downtubes but it's not insurmountable.
My pick is to use a circa 71-74 MK series Husqvarna frame. I've seen a few of these conversions and the actual swap seems to require less surgery than most of the others. One of the quirks of Husky handling is their slow turning ability, needing a bit of body english to place some extra weight over the front to rail the berms. It's not a fault, it just requires a style adjustment from what you usually do. However, it's been found that the fitting the much heavier Honda 4t engine turns the Husky into a cornering weapon, they turn much quicker than a stocker...one of those little bonus's that often pop up from an engine swap that you least expect.
Having said that, the most successful four stroke Hondas from the golden era of pre '75 nearly all featured stock frames. It's surprising how much weight can be chopped out of a stock XL frame and once fitted with decent forks (Ceriani, Betor, CZ), lightweight hubs and plastic or alloy tank and light plastic mudguards and side panels the XL stocker isn't as mundane as many think. Back in the 90's Steve Greentree raced a beautiful pair of XLs that were practically unbeatable, even outside of the 4 stroke class. These bikes rocked and inspired a lot of other builders to use Steves subtle tricks to get the old trailbike working well.
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Doesnt Col metcher has a maico with a HOnda in it ?, ask him from some pics of that to see if its of interest.
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we've got a honda running in husky frame over here in the West has run very successfully
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I have been looking at Pursang frames as possibility for TM400 engine. So interesting that the XL will fit as it is bigger, heavier and slower than the TM.
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Here is the Greentree one
(https://blufiles.storage.live.com/y1pzJeiEvyw-vh8_IIRafIaDK-Q2y8xowyLHGNmCb2btrSXvNPzVYEOBvSIvyReDHKF6SU4fdJTCmQ/green1.JPG?psid=1)
I am keeping the stock frame aswell on mine. I think its plenty good enough.
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looks more like a CrZ in its styling.
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I was going to use a Husky frame before I got my C & J frames, Husky frames are cheap on ebay & they come up often, my sideport C & J turns much better than the Baja bike due to the rake & heaps better than the stock frame XL sideport I used to race two years ago.
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i used a TGM frame..which was quite easy to do , i've put honda engines in maico,husky and used stock frames with extended swing arms but nothing beats the handling of the C&J...however the TGM framed bike i've built handles pretty well....
I was looking at Can-Am frames and reckon a honda engine would fit with a bit of beard stroking ..
pics of the TGM/XL below
(http://i1016.photobucket.com/albums/af289/saloon3/002-2.jpg)
(http://i1016.photobucket.com/albums/af289/saloon3/002-1.jpg)
(http://i1016.photobucket.com/albums/af289/saloon3/carb.jpg)
(http://i1016.photobucket.com/albums/af289/saloon3/017.jpg)
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Thats a sweet looking bike Davy. 8)
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the South African rider Rob Wicks
This one ? looks sexy to me ;D
(http://i146.photobucket.com/albums/r259/vmx247/TeamSA.jpg)
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Hay Guys,
Thanks for your help, Mark seems to be talking sense about the original frame but shit I have my heart set on making a special I am how ever very limited to what frames are available down here in Tas I have a good friend that is going through 2 sheds full of old spares looking for me I have asked him to look for any pre 75 MX frames hopefully something will turn up that hasent seen the light of day for a while. But if you guys have a frame and swing arm that might be suitable please dont hesitating in sending me a message.
I love the TGM/xl and the C&J Honda I wish that one of those frames was to come up. A guy over here has a champion frame but wont sell it even though he has had it for years and hasnt used it.
Cheers
Fatboy
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Heres a good few pics of a can-am frame on this ebay link ..he dreaming with the price as there are loads more starting at $50 us..
http://www.ebay.co.uk/itm/1974-Bombardier-CAN-AM-TNT-175-Frame-/190537493716?pt=Motorcycles_Parts_Accessories&hash=item2c5ceb6cd4
plenty room in the frame and swing arm spindle to bottom frame rail geometry looks close to allow honda motor to fit..
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Shane - get a YZ ;D
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plenty room in the frame and swing arm spindle to bottom frame rail geometry looks close to allow honda motor to fit..
I can see a couple of problems with the Can-Am frame, the first being a possible exhaust clearance issue with the twin downtubes fouling the off centre exhaust. The second might be a clearance problem with the tall Honda engine fouling the diagonal downtubes going from the top frame rail to the swingarm pivot area.
Even if the engine slips inside of those braces, it'd be a nightmare getting it in and out. If those braces were removed or relocated, frame strength might be compromised.
The difficulty with the Honda's motor is to get the wet sump as low in the chassis as possible to help align the sprocket with the swingarm pivot to achieve the best chain travel. There's a lot of engine below the crank/sprocket centreline on an XL Honda engine which usually means removing any lower rail cross braces or at worse, lowering the whole bottom cradle. The Montesa and CZ both seemed to be easy swaps with the motor slotting in pretty well but in both cases the engine sat too high because of that big lump of sump. Both frames weren't wide enough for the sump to fit between the bottom frame rails so the bottom rails had to be lowered. Besides those two frames I also measured up DT250A Yamaha, Honda CR250 Elsinore, Bultaco Pursang MK5, Bultaco M11 and Rickman Montesa frames and each failed for either exhaust and/or sump clearance problems that would require major work to cure.
Maico and Husky frames feature large engine cradles and wide lower frame rail spacing making them much easier propositions. There are others that may fit the bill...possibly the little Rickman Zundapp which seems to be able to accept everything from DT1 through to 500 Triumph engines. I also think the Sprite/American Eagle might fit the criteria except that it's probably heavier than the Honda frame, which isn't all that heavy in itself once the gizmo brackets are removed.
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options and more options
http://cgi.ebay.com/ebaymotors/1972-Husqvarna-WR450-MJ-FRAME-CR-WR-RT-Husky-swing-arm-Ahrma-VMX-/350493071693?pt=Motorcycles_Parts_Accessories&hash=item519b03d94d
http://cgi.ebay.com/ebaymotors/78-250-Bultaco-Frontera-MK11-chrome-alloy-frame-VMX-/170570750865?pt=Motorcycles_Parts_Accessories&hash=item27b6cf1b91
http://cgi.ebay.com/ebaymotors/1977-Bultaco-370-Pursang-Frame-Ahrma-Vintage-MX-/350493105645?pt=Motorcycles_Parts_Accessories&hash=item519b045ded
http://cgi.ebay.com/ebaymotors/Vintage-MAICO-1968-1971-Frame-MX-AHRMA-Stock-OEM-NO-cracks-repairs-/320764195964?pt=Motorcycles_Parts_Accessories&hash=item4aaf09347c
http://cgi.ebay.com/ebaymotors/AHRMA-VINTAGE-1972-Rickman-Zundapp-125cc-MX-FRAME-/230406315571?pt=Motorcycles_Parts_Accessories&hash=item35a5495e33