Correct carbs for 750E-II???

Hi all, I've just got me a tidy low mileage XJ750E-II (like 21,000 miles, original front tyre never mind the brake lines!) that's obviously stood a long while since being imported to the UK in 1990, but fortunately in a dry garage so it's really tidy & rust free generally.
Although I'm new to Yamahas with this bike, I'm not new to bikes/carb cleaning/general mechanical & electrical work etc


The problem I have is that according to the specs given on here, the E-II carbs are as follows-:

Years & Models: 1983 XJ750E-II models
Carb Manufacturer: Hitachi
Carb Series: HSC33
Carb Model ID: 29R00
Main FUEL Jet Size: #105 (cylinders #1 & #4)
Main FUEL Jet Size: #102 (cylinders #2 & #3)
Pilot FUEL Jet Size: #40
Main AIR Jet Size: #70
Pilot AIR Jet Size: #225
AIR COMPENSATOR Jet Size: not used.
Starter FUEL Jet Size: #43 (non-replaceable, in float bowl)
Main jet NEEDLE ID: #Y-17
Main needle JET Size: #3.2mm (the main needle JET is also known as the "power valve" or "emulsion tube").
Fuel Level in float bowls: 5mm +/- 1mm (.197" +/- .039")
Idle RPM's: 1,050 rpms

This would seem to be right due to the 29R code, However on removing the carbs this afternoon to clean them (they weren't bad, 1 stuck drain screw, pilot screws perfect & had rubber plugs, they've obviously been off before as inlet stubs were loose (no snapped bolts though!) and few other clips loose) and not bad inside for an amateur job (apart from the switched main/pilot air jets, corners and cold start passages in the float bowls that is). And after cleaning I've run the bike for a few seconds but now waiting to get new fuel lines & filter as it all leaks.

However, I'm confused now because the carbs DO have the compensator jets in the mouth & the jetting doesn't tally at all.

So I'm wondering, is the info I have wrong, or has someone done something stupid to the original carbs and maybe bunged a random set of hitachis that looked similar on?

Cheers for any suggestions, Dan

P.S. will get pics tomorrow if I get time, she ain't bad though for £510 I reckon

 

Well it looks very much like I have carbs from some kind of 650 model according to the jetting & spec lists on here :?

Going to contact p/o and see what he reckons to have done...

 

Right well, he claims not to have changed the carbs but did have a spare set of dirty ones that supposedly came with the bike when he got it although they "could be 900 ones" as well :roll:

Anyway £10 for a set of breaker carbs didn't seem too bad, and on initial inspection when I got home the gunk inside smells looks and feels like the much less nasty stuff you used to get with leaded juice. none of my pistons on either set have bad rubbers or split retainer rings and even the enrichment jets are reasonably free so at least if I clean this lot up I have a swapper set to help persuade anyone who has the right ones to maybe part with them... The jetting looks to be XJ750 at least on these ones 8)

I even got a throttle cable, set of new front brake pads & Haynes 750 and 900 manuals, can't complain :wink: Still wish I had the correct carbs though...

 

Across the pond, our 650's and 750's had 32mm carbs with different jetting. Have you measured the carb throats? That's the barrel that mounts inside the mounting boots.

 

Both sets are incorrect HSC32's, the set fitted is jetted for a US spec 650 & the ones I've just picked up, although sh*tted up, are jetted for UK spec 750.

So for now I think that a good starting point to at least get the bike running would be to swap all the jets & needles etc from the dirty set into the 650 set I cleaned (and swap the float bowls too for the correct enrichment jets) after all the 750E-II engine is going to be closer to another 750 model in it's fuelling requirements than any of the 650's.

With any luck I can get the bike up and running on these carbs while I try to track down the correct HSC33's (and clean out my spare carbs as a possible swap/deal item for those)

On the right track do you think?

 

My 700 Max was supposed to have Hitachi33's, but the PO had put on Mikuni32's from God knows what. It ran fine til the carbs got dirty and then I went on a mod craze.
The mounting boots for the 33mm carbs are no longer available, so most people over here are converting the boots and carbs to the 32mm. Maybe that's what happened in your case. If the 32mm carbs will mount up with the boots, i would clean, re-jet and install. They work over here, so they should work over there. 8)

 

Can you post some pics of your carbs so we see what you have?

 

Can't get pics to upload from phone to computer unfortunately. I'm 99% that they're from the bikes I've stated though as both are 32 (and fit tightly in the intake stubs) and have compensator jets in the venture (STUPID AUTOCORRECT, I SAID VENTURI LOL) ring. The jetting closely matches the stated jetting on chacal's carb thread for those models too.

Like you say, I don't see why carbs from another (less "hen's teeth") model XJ750 wouldn't work with this engine. Only difference I can foresee provided compression & timings are the same is I'd end up with slight improvement in torque with less top end, which would be fine by me anyhow

 

Good luck and let us know how it turns out.

 

Thanks, I will do. I just found an old post from a member called wolfie who had an XJ900 frame with a pair of 29R engines, weird thing is he is/was actually in the same area of the UK as me!!!

http://xjbikes.com/Forums/viewtopic/t=17807.html

Unfortunately he doesn't appear to be on here anymore or I'd probably buy up his 29R parts so he can get a proper 900 motor & I get my carbs & some spares... Such is life

 

Yamaha did some (parts bin) bikes. Whatever was left over got cobbled together. But that shows us what parts can be substituted on other models which will come in handy when original parts can't be obtained.
I'm confident that those 32's will work, after all I made a 2 carb conversion work on my 700.

 

That's true, it is just possible that the spare carbs jetted to 750 spec could even be the originals from the bike, seeing as the rubbers appear to fit...

Time will tell, but given the apparent rarity of these models I would have liked to get in touch with wolfie to try and get it back to factory stock (maybe NOT as far as the fusebox though, I'm not like those anal Kawi Z bunch yet lol )

 

Here's an interesting tidbit for you...

Looking on the XJCD set, there's a file on there listing the Japanese home market models with a short description. For the E-II model, they have this:

----------

XJ750E-II (1983)

1983 saw the 750E grow into the E-II model. Fitted to the larger frame used elsewhere for the 900R, the engine grew to 749cc thanks to a 0.1mm extended stroke. Larger valves, reworked cams and slightly larger Mikuni carbs bumped the power specifications to 72.0ps/9000rpm and 6.20kg*m/7000rpm. Unlike the 1984 XJ750RL exported to some markets, this model retained the anti-dive front forks of its bigger brother. In fact, the only obvious difference is the muffler design.

----------

So... is it Hitachi or Mikuni?...

 

Thanks man, coincidentally Shane (the guy in NZ I've been talking to, used to be "Kiwi" on here) just sent me the exact same passage of text with some pdf files from his ownership of one of these & I noticed that said Mikuni as well.

It is in fact wrong, and the original carbs from various sources (including shane's bike which had the original carbs) are Hitachi HSC33 with code 29R00.

Cheers for looking this stuff up, every little helps with this bike!

 

Anyone know where I can get part numbers for the exhaust system?

 

@ atonydins Left exhaust is 29R-14711 and right is 29R-14721, there was a company in the UK parting out a 29R on ebay.

And have HSC33 Carbs on mine.