CB750 scrambler project
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@markus-w thank you, I still need so many parts.
I have no experience with these bikes so i don't know how anything goes.
I need all the brake/ clutch hoses, front will have to be custom.
Levers, pedals, footrests, controls. Cables.
The biggest headache is the electrics.I can't understand why it's a push pull cable on the diagrams when the CV carbs are sprung loads on the butterfly valves. Doesn't make sense.
This engine is all new to me, I can't get any information about what year and model bike it is. Engine code is RC17E.
I'm not entirely sure if this is a breather pipe or a return pipe ..,.
Can see it on diagrams, it looks like it bridges the two sides of the cylinder assembly.
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@Louis-DT-WR I think it is spring loaded as well with the push pull throttle cable or how else would the throttle shut off when you let it go? Or have I miss interpreted you?
@markus-w it only needs a single pull cable same as the DT but the diagram shows 2 cables.
This pipe in the front of the engine must be a breather I can't see what else is would do.
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@markus-w it only needs a single pull cable same as the DT but the diagram shows 2 cables.
This pipe in the front of the engine must be a breather I can't see what else is would do.
@Louis-DT-WR you're probably right on it only needing one cable but U.S DOT requires two by law incase the spring fails or throttle slide sticks. Contrary to their name they don't actually push, when you shut off throttle the push cable actually pulls the throttle closed. As for the dtr having single cable maybe they weren't sold in U S.A or maybe that law comes in for bikes of a certain size/power. My 1989 nc30 had two.
And yes it is a breather pipe, they sometimes are routed back into the carb manifold so any nasty emissions are burnt off. Hope this helps. -
@Louis-DT-WR you're probably right on it only needing one cable but U.S DOT requires two by law incase the spring fails or throttle slide sticks. Contrary to their name they don't actually push, when you shut off throttle the push cable actually pulls the throttle closed. As for the dtr having single cable maybe they weren't sold in U S.A or maybe that law comes in for bikes of a certain size/power. My 1989 nc30 had two.
And yes it is a breather pipe, they sometimes are routed back into the carb manifold so any nasty emissions are burnt off. Hope this helps.@markus-w great thanks but I have a dt200wr which was sold in the US and that wasn't push-pull.
The carbs to have slots for two cables day + choke cable.the CB 750 doesn't seem to have that breather pipe, but on this cbx750 it does.
Brains hurting from all the learning on this build haha.
I'm happy the rolling chassis is done.
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@markus-w great thanks but I have a dt200wr which was sold in the US and that wasn't push-pull.
The carbs to have slots for two cables day + choke cable.the CB 750 doesn't seem to have that breather pipe, but on this cbx750 it does.
Brains hurting from all the learning on this build haha.
I'm happy the rolling chassis is done.
@Louis-DT-WR my thirst for knowledge has got the better of me I've just done a bit of googling and apparently it's only four strokes have 2 cables because the extra vacuum created by a 4 stroke can cause the throttle slide to flutter and jam against the side of the body. That seems to me the most logical explanation so far.
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@Louis-DT-WR my thirst for knowledge has got the better of me I've just done a bit of googling and apparently it's only four strokes have 2 cables because the extra vacuum created by a 4 stroke can cause the throttle slide to flutter and jam against the side of the body. That seems to me the most logical explanation so far.
@markus-w possible. The other thing with this engine is why does it have 2 oil fillers caps
️ 1 says (don't open) but that's the sprocket side.
In some pictures I see that's where the dipstick is on some bikes. My dipsticks on the clutch cover side like most bikes.Haynes don't do a cbx750 manual.
Just going to persist working through all the small bits. -
@markus-w possible. The other thing with this engine is why does it have 2 oil fillers caps
️ 1 says (don't open) but that's the sprocket side.
In some pictures I see that's where the dipstick is on some bikes. My dipsticks on the clutch cover side like most bikes.Haynes don't do a cbx750 manual.
Just going to persist working through all the small bits.So the carbs were very similar but not correct.
So I started again
parts are taking so long to come from overseas
All new float bowl gaskets, diaphragms, o-rings and rejetted.
Powder coated partsStainless steel Allen cap bolts
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@Darty yes but 4 cylinders is a nice compensation
I've got a name for her.... "Lucille"
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I mean, yeah I agree two many strokes.
But doesn't stop this being a really interesting and cool build.
Loving it pal, keep it up!
@Calum cheers man, will keep posting when I get some big progress, stupid Chinese virus is holding up my parts
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Finally my bar clamps came, 3 weeks.
I've got the controls, grip, master cylinders on. Front brake operational.
Choke and throttle cables.
Front headlight on the number board (not finished yet) more to add to it.Pro taper contour bars.
Rear fender (when pulled out, it's a shovel! (Entrenching tool))
Slowly making progress.
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Finally my bar clamps came, 3 weeks.
I've got the controls, grip, master cylinders on. Front brake operational.
Choke and throttle cables.
Front headlight on the number board (not finished yet) more to add to it.Pro taper contour bars.
Rear fender (when pulled out, it's a shovel! (Entrenching tool))
Slowly making progress.
@Louis-DT-WR i like the shovel rear fender adds character
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Been driving me crazy how the seller of the engine said it was from a cb750 but appears to be a cbx750 engine (much older + hydraulic clutch) rc17/17E
But the engine apparently had only done 12k
Also looks very new for something that would be 40 years old nearly.After a lot of research the Japanese did a later 2007 LTD with the Rc17E engine when looking at the part numbers for the upper crankcase on this models parts diagram it confirms this.
This is a super rare models engine, + hydraulic clutch optional extra. On an import!But it will work perfectly for me, just ordered the correct pulse generator.
Writing this down for future reference because I'll forget. -
Started on the looming and electrics.
Repositioned the coils to clear the fuel tank.
Little jobs like that take a lot of time getting right.My holster on the headlight number board is all part of the walking dead style bike. It definitely wouldn't be ridden with that on it
even though I'm trained on glocks , this is just a replica.
Only used for pics
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Started on the looming and electrics.
Repositioned the coils to clear the fuel tank.
Little jobs like that take a lot of time getting right.My holster on the headlight number board is all part of the walking dead style bike. It definitely wouldn't be ridden with that on it
even though I'm trained on glocks , this is just a replica.
Only used for pics -
@Louis-DT-WR this looks amazing, well done
@rolz82 thank you, working through all the electrics. My least favourite thing
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Working through the electrics. I've got my rear indicators and tail lights sorted.
I made a CDI holder to relocate it.
Fuse box and indicator regular relocated.
Front lights, indicators and horn on.
Ignition barrel relocation plate made.
Just sorting a battery box and the battery is on order. I can't fully test what connector goes where until the battery comes.
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Well I put the engine in alone which was a very heavy task
killed my back haha. Lining it up with the mounts while the bike was leaning again the bench. (You can't fit the engine when the chassis is on a bike lift)Got my battery box mounted with the lithium battery. Its so light! I thought it was just a empty case!
Carbs on + filters and cables. Fitting the carbs was tricky, the rubber manifolds are so hard. I'd replace them but £150+vat for 4 and they're not cracked.
