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Time For Carbs...... Bike Carbs!


stu205
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Righto having weighed up all the pros and cons of srtaping a set pf twin 40s to my 2ltr pinto and running the bike t/boddies Ive got in the kitchen and have thrown both ideas out of the window and am settling for bike carbs instead

 

having tralled the net for info and as per usual getting 30 different answers was wondering if i can tie up a few cold hard facts

 

Im looking for bikes that had a 39mm or 41mm inlet (such as R1) but dont want to pay a premium for the R1 carbs ive been told that Kawasaki 900cc bikes had them as did a few Yamaha 1000cc ones any one have anything more specific?

 

Ill be sending them off to Bogg Bros for rejetting and a manifold but they are having problems getting R1 carbs for normal money too, there the guys who put me onto the Kawasaki route, but the ZX7 only has 38mm inlets but would 38mm be large enough for a 2ltr???

 

any help welcome

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Stu,.

The one significant point to bear in mind is that choke size on the output side of the carb should not be larger than the inlet port size of the head. The average Pinto head is about 37-38mm, so work by that.

 

I chose a set of Mikuni's off a 1200cc Yamaha, with 36mm choke, this ensures that the fuel is properly induced allowing for the step in the manifold where the carb chokes enter it, rising to about 38mm internally to match up properly with the final mating surface on the head.

 

A larger choke size to start with means working in reverse which is utterly pointless and in fact restricts the flow.

 

On the previous posting (the link) mentions this point.

 

You'll have to fork out about £120-£150 for a decent set of s/h Mikunis or you could go for Keihins as an alternative.

 

Picture included of the ones I bought off EBay for £165.

 

 

Mick.

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I've recently installed bike carbs - I got a set of 36mm Mikuni BSR carbs off ebay, and they seem to be fine for my 2.0iL, pulls all the way to 6000+rpm once rejetted (main jet around 1.7mm).. I still need a tad more ign' adv' though..

 

A pic of my install is on my garage profile.

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yeh I spoke to Bogg about them and they sudjested the Kawasaki and Yamaha ones to look for but didnt go into sepcifics about which ones to go for, aparantly there having real problems getting R1 ones as everyone has started asking silly money for them

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Stu,

although the DCOES are called 40s, thats the overall size.

You need to fit an internal choke, and for a mildly tuned engine, you'd fit

36mm chokes . For a wild engine youd go up to 38mm. See Dave Andrews site for more info.

As an example, I have 45s on my XE but have 38mm chokes fitted.

HTH Bob.

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36 / 38 mm carbs are quite plentyfull and still reasonable prices. I recently got a set of 38mm Mikuni's(yamaha fzr 1000) for £40 and paid about the same for a set of 36mm mikuni's from a gsxr 600.

 

Mikuni's are the ones to go for because they use weber compatable jets.

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Hadn't thought about fitting bike carbs as replacements for my single Weber, but am keen to try them so 4 questions

 

1 What size are best for 2.0litre Pinto fitted with single Weber, 36 or 38mm....does it make much difference? :huh:

 

2 Someone said to me that slide valve bike carbs were the ones to go for......who makes these or which bike would they come off :mellow:

 

3 If I take off the inlet manifold what happens to the water hose that connects to the heater matrix....do I just block it off.......I seem to remember in one of the other tips someone mentioning it was best to leave it attached as it forms part of the cooling circuit for the Pinto engine ;)

 

4 Does anyone do ready made template / mounting brackets with stub end to allow carbs to be attached to the block or do you have to fabricate these yourself? :unsure:

 

 

Cheers

 

Robert B)

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Boggs Brothers... do a google. Not cheap though.

 

Mikuni's seem to be well thought of...

 

All this info is in the posts above...

 

You need to leave the water connection in place, it cools the head before the stat opens. If it's going into the carb then that's because you have an Automatic choke type, just connect it up without the carb in the middle... leave the heater in if you have one, if not just a loop of rubber.

 

If you mean the brake servo pipe that goes to the manifold or the breather pipe, you'd need to connect the servo pipe to the new manifold or go servoless with a longer push rod from Tiger (or get an engineering shop to turn you one up, not much to them...), as for the breather pipe you can vent this to a catchtank as you would with twin 40's.

 

Lots of info on breathers & catchtanks etc in the Burton Power catalogue (do a google & order one, catalogue is free...)

 

Dan :)

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Bogg bros "kit" is about 300 quid which considering what your getting seams a fair one to me, although I am going about it in a hoody fassion, ebay carbs, EFI intake manifold and an angle grinder :D :D

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I used a half recycled EFi manifold to start with, and fiber glasses some plastic pipes in to it, to join up the carbs with some hard hose.. It worked suprisingly - enough to get the carbs and ignition sorted out. Ended up driving about 400miels on it..before the enivitable cracks..

 

I remade the whole manifold in mild steel, with curving tubes to make the port spacing match..-- works :)

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my carbs have just arrived (mikuni's from a zx600r) and been giving them a good look over, most things I can sus out, idle control, fuel lies, choke etc but there 2 hoses im not sure about, one muss be a vacume but dont know which and what to do with the other?? also theres a small electronic plug at the end that Im assuming is the throtle position sensor that wont need to be used??

 

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