Restricted AT RD07

[Paddymac]

Hi, last year I bought an AT which had previously been imported from Switzerland. I very quickly realized there was something strange when it wouldn't pull over 80mph. I heard then that Swiss bikes are all restricted - don't know if that's true of all bikes, but on removal of the carbs discovered that the carb rubbers were choked right down.

New rubbers from Wemoto has helped it a bit (will now do 90mph) but I suspect it's now running lean and needs re-jetting. I've considered buying a Dynojet kit, but I wonder whether that'll open a new can of worms.

Does anybody have experience of this issue? Would I be better off putting standard jets from a similar aged uk model? Is it likely I would need to change the needle valves as well?

Obviously to prevent holed pistons etc, I need to sort it out before I can do any mileage on it.

I see this issue has been covered with RD03 models

It has a standard exhaust and air filter at present.

Thanks in advance

[Knobblywobbly]

AFAIK, It´s German models that are restricted, not Swiss, and the restriction is done in the carb rubbers as you´ve found. These simply restrict the amount of fuel/air drawn into the cylinders - removing them allows more mixture to be drawn in, but the original fuel/air ratio should remain the same, i.e. removing them shouldn´t make you bike run lean. There is talk of Austrian models being restricted further by using different camshafts ( ATiC - Honda Africa Twin Homepage), but looking through part number lists there is no difference between the part numbers for Austrian models and all the others.

Have you checked the gearing, i.e. sprocket sizes? Also, maybe it needs a good service (new air filter, valve clearances set, etc.).

[Lutin]

According to the Haynes manual, it was German models (though not all) that were restricted.

The restricted models have different engine and frame numbers -

1993, XRV750-P, Engine number: RD04E-33, Frame number: RD07-30

1994, XRV750-R, Engine number: RD04E-34, Frame number: RD07-31

1995, XRV750-S, Engine number: RD04E-35, Frame number: RD07-32

The unrestricted engine and frame numbers have a leading "2" rather than a "3".

Hope that helps.

[Kjell Lindberg]

Ok here is what you have I guess:


50HP

And this is what you need:


Full power...

I never heard of RD07 restricted to less than 50 HP, but I find it likley that there were also 27 PS (Pferd Stärken) versions for lerners/beginners.

No information on Jets for restricted versions.

DynoJet... I would not install them, my mechanic tells me they are a fast and expensive way of ruining ones carbs, and I trust him.

But that's just my very own personal viewpoint, and there are a lot of owners that really like their DynoJet kits.

Before you buy and install, check accurate XRV750 Dynorun figures first and decide if it's worth the money and work involved.

DynoJet and a good End can, would perhaps add 3-5 HP.
(I would love to see higher validated figures, 'cause I buy the parts in a blink)
A bad End can could take the same HP away.

My 2 pennies worth... //Kjell

[Paddymac]

Hi, thanks for all the help with this guys!

Yes the Kjell the photos you posted are exactly what I found the first time I took the carbs off, and the new Wemoto ones I've now fitted ones look like the right size now.

I've taken the carbs off again now to look at the jet sizes that are in there. It is as you say they are the standard sizes for the year of bike - front carb: 118, back carb: 120.

Have got the plugs out as well and they all seem to be a good colour.

So! why does it start to run out of puff at about 90mph? It is true that I had been reluctant to push it hard in case it was running lean. It pulls cleanly right thro' but the vibration goes up a lot at 90 and I assume it's struggling - I'm not desperate for the speed, but I would like to know it's running as it should. What sort of top end speed should I expect it to pull?

I shall check the gearing next, tho' it doesn't seem like it's got low gearing, I'd actually say it feels quite long legged (which I like). Perhaps it's geared too high and it's stopping it revving out. The Transalp I had just prior to this A/T was certainly a livelier motor and would pull the ton with no real problem. Does anyone know what standard gearing for this should be.

Who's bright idea was it to put that front left spark plug there?!!!... If just getting the plug out is that involved I don't know if I even want to 'go there' with checking the valve clearances! Dare I ask how awkward that job is?

Thanks again

Pat

[Xman]

Sounds to me like you iether have carbs that are out of balance, or your gearing is so low that you are expecting a Vtwin to rev like a multi cylinder.

My RD07 is as high geared as I can get it without having to slip the clutch too much to pull away, but it sits at 80mph very smooth. Anything over that is starting to get a bit vibey which I accept because of several reasons...mainly it's a 750 with 5 gears, it's not aerodynamic, and it's a v twin!

[Paul-S]

16 t front and 46 t rear are standard

I run 16 t front and 45 t rear - standard jetting, K&N, Remus Grand prix exhaust, tall screen, just over 50,000 miles now

5,200 rpm = 70 mph (all mph = satnav mph)

6,000 = 80 mph

7,300 = 100 mph

8,000 = 112 mph flat out