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Old 03-17-2009, 07:30 AM   #946
bluesman
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Quote:
Originally Posted by ppe172
you should be installing the next size larger pilot jet(s)

How do you change the pilot jet on a BST33 carb (DR750)? I've had mine apart and changed the main jets but there doesn't appear to be a pilot jet. The carb diagram doesn't show one in the factory service manual.
I do not know - I did not see/touch it either...I only played with main jets and needle.
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Old 03-17-2009, 10:14 AM   #947
Ladder106
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Pilot jet

The pilot jet (sometimes referred to as the slow speed jet) is normally hiding well up inside the carb toward the intake side of the carb body.

Turn the carb over and you'll see the main jet sticking down in about the center of the carb. Look toward the intake side of the carb moving from the main jet and down inside a cast aluminum hole (tube) you'll see a small brass slotted screw. Pick the "perfect" sized screwdriver with a nice square edge to unscrew the jet.

If the jet has been in the carb for some time it may take a bit of force to break free....but use CAUTION because the jet is soft brass and the last thing you want to do is strip the screw head off the jet.

Some CV carbs I've seen have, for some reason, a plastic cap over the access hole to the pilot jet so if you see one of these, pop it off carefully and look down inside.

The pilot jets are TINY, about the size of a pencil tip and have a very very small hole (jet). Don't shove anything in there to "clean" it out. You can easily scratch the jet and greatly alter its flow rate making any logical jetting changes drive you crazy.

Also there are a number of different main and pilot jet types used in carbs so if you have jets hanging around, don't automatically assume that they will fit. The length, diameter and position of the bleed holes (if any) in the side of the jet is important...not just the size. Use one that matches exactly.

While you're there also look at the condition of the needle (hanging down from the slide) and the needle jet (the piece of brass that the needle slides down inside). Both of these pieces of metal will physicallywear. This wear is worse on large single cylinder engines since the intake pulses rattle the needle back and forth inside the needle jet and brass is soft. If the needle has a very shiny spot that looks worn (thinner) or the hole in the brass tube is egg shaped - even slightly - replace the needle and needle jet.

I've seen guys drive themselves to distraction trying to jet a carb with a worn needle and needle jet. The wear keeps changing the jetting randomly and makes your alterations not make sense.

For some reason the service manual does not show the pilot jet in the exploded diagram....rest assured that it's there.

If you have trouble, I have a set of carbs from my Transalp that I can open up and take a photo.

Enjoy.

Ladder106 screwed with this post 03-17-2009 at 10:37 AM
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Old 03-17-2009, 11:30 AM   #948
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All I know - just for info - stock pilot jet on DR800 from 1990 is #40, on 1992 -on SR43 is #45. Since I never had trouble with idle I did not touch it.
On Keihins I had on some other bikes I used to own it was more interesting...with more air adjustment available using easily accessible screws and less fuel adjustments available :) and to be honest I still prefer Keihins to Mikuni.
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Old 03-17-2009, 11:46 AM   #949
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Quote:
Originally Posted by bluesman
I still prefer Keihins to Mikuni.

Mikuni is the Japanese payback to the world.

They perform quite nice but sometimes they could be a pain in the ass.
I don't know about Keihins but Dellorto (on my KTM Sx and on all go-karts that compete in Estonia) performs as well and it's easier to tune.
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Old 03-17-2009, 11:55 AM   #950
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Luggage system

New subject here I think.

I've been thinking about Hepco & Becker Gobi.
What would you guys prefer for DR BIG.
Is there a solution just as good for a smaller price?
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Old 03-17-2009, 01:13 PM   #951
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Ladder106,

Thanks for the reply. I don't (I think) have any issue currently which would require me to change my pilot jet(s) it's just that when I had the carbs open before I could not see any. I have changed pilot jets in other carbs so I know roughly speaking what I should be looking for but again, with the DR750, no joy. Unless your Transalp uses BST33 carbs, or something that is basically the same, I don't know that pictures of those would help. However, if you, or anybody else, happen to have one of these carbs open, and can take a picture showing the pilot jet that would be great. As I said, I don't have any urgent need for this but for future reference it would be good to know.
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Old 03-17-2009, 01:13 PM   #952
RaY YreKa
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Quote:
Originally Posted by morse
New subject here I think.

I've been thinking about Hepco & Becker Gobi.
What would you guys prefer for DR BIG.
Is there a solution just as good for a smaller price?


I was thinking the exact same thing; H&Bs plus the Gobi bags would be the most expensive mod of the ones I'm considering, though the bags could at least be transferred to another bike a few years down the road.
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Old 03-17-2009, 01:48 PM   #953
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I think no matter what bags/system you use...as long as you can adapt carriers frames to DR.
I like Givi frames style setup because they act as crashbars for rear of the bike and proved itself on quite a few occasions in this role :)
I think their "mushroms" suspension system for bags sucks. Big time, at least on DR. Because of vibrations those "mushrooms" getting eaten through in like every 10000 km with luggage.
I think key question is - what is aim, paved roads touring or "do it all" kinda luggage that actually may not be best at everything.
Since I treat my DR with principle "everything not directly functional must be cheap" I am so far quite happy with my set of 100 Euro-per-pair secondhand Givi bags + self-remade ex-5star junk carriers.
H&B seems kinda too nice and fragile...same goes for SW Motech (since they compatible with Givi system), thou their mounting system seem nice and I had good feedback from my friends on those. Advantage of both systems is - you can actually totally improve bags mounts without touching carrier, because adaptor plates/racks are click-on (or bolt on? Fast release).
Generally so far SW Motech stuff seems to be better made that H&B except cases itself, which are very much same...
Price bites, but I seen a lot of this stuff on German eBay at way more reasonable prices than you would expect.
As for Gobi bags - think if you really need super-cool double-walled water carrying bags unless you about to cross desert. Well, of course filling it up with good vodka or canadian whisky will be an option
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Old 03-17-2009, 05:19 PM   #954
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I'm going to bid on one of these Crashbars.
If someone would like to do the same I think it would be smart for us to decide whos going to bid on wich one.

http://cgi.ebay.de/ws/eBayISAPI.dll?...m=160322324916

http://cgi.ebay.de/ws/eBayISAPI.dll?...m=160322327058
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Old 03-18-2009, 10:21 AM   #955
RaY YreKa
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DR Big goes on the Dyno

So, I was out and about today after having the oil changed and a general check-over at my friendly neighbourhood back-street mechanics (B&C Motorcycles in Manchester). No problems with the bike, though they recommended I replace some fasteners with stainless items from probolt.

I did about 30 or 40 miles pottering about, mostly on A roads just rolling on and off in 3rd and 4th gear. No backfires from the ProDuro, seemed to be running well. I found myself at the Rocket Centre in Blackburn, and remembered they have a Dyno machine..

Hmmm

So, for the sum of 25, I got the 800 on the Dyno.





Results next...
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Old 03-18-2009, 10:32 AM   #956
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OK, here's the print-out for bhp and feulling. I should point out that the Dyno Operator said the probe couldn't fit round the kink in the ProDuro, so he couldn't trust the results 100%.

But the fuelling was basically good, just a little bit rich, which he said wasn't a bad thing as that would make the DR run a little cooler too. With overheating being a problem, I can live with that. He said using a dynajet kit would probably make it run even richer, and that if he was to reccomend anything it would be to go down one size on the jets "if you can be bothered".

The best bhp run was a bit disappointing, 42.05 at the rear wheel. I don't know if this is normal, as the figure is 53bhp at the crank? Anyway, not to worry, 5500 rpm is still 60mph in 4th gear and closer to 80mph in top, and the bike does just fine.



Below is the torque, with a best of 39ftlb at about 5500 rpm. I expected a bit more here; maybe I'll just blame that probe . It has a nice curve though (the jagged edges are probably the chain jerking about), which I guess is what you feel riding.



So I'm not going to have any Dyno work done, not unless I buy those flatside carbs somewhere down the road (and the GPR exhaust looks nice!). It was fun in the Dyno room, the staff were good enough to let me in to watch and take pics
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Old 03-18-2009, 10:36 AM   #957
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Oh, and congrats to all you guys on here - this thread has over 50,000 views now

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Old 03-18-2009, 10:44 AM   #958
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42 at rear is totally OK. If you estimate 15% loss cranck to rear wheel we talking 49.85 BHP at crank. Totally OK, plus if dyno operator was realistic and correct guy - his stand would have totally realistic results.
Are you running KN filter? Just FYI - by itself it is no better than stock and if in original airbox - bike would not gain any advantage from KN except that it is re-usable. If you look at aitbox - snorkel is tiiiiny. My bike had totally clearly visible air starvation with Arrows can until I opened up airfilter, then it decided it wants more fuel. This would explain why peak bhp on your bike was lower in rpm range than usually expected from DR800 (usually it is at around very top rpms where it hits peak).
Torque graph looks totally correct rpm/peak wise.
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Old 03-18-2009, 10:54 AM   #959
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Monstablokaz estonia 800 30

What does this red 30 mean??
Cant wait the snow to go away already, I haven't ride my bike since october

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Old 03-18-2009, 03:44 PM   #960
RaY YreKa
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Quote:
Originally Posted by bluesman
42 at rear is totally OK. If you estimate 15% loss cranck to rear wheel we talking 49.85 BHP at crank. Totally OK, plus if dyno operator was realistic and correct guy - his stand would have totally realistic results.

Are you running KN filter? Just FYI - by itself it is no better than stock and if in original airbox - bike would not gain any advantage from KN except that it is re-usable. If you look at aitbox - snorkel is tiiiiny. My bike had totally clearly visible air starvation with Arrows can until I opened up airfilter, then it decided it wants more fuel. This would explain why peak bhp on your bike was lower in rpm range than usually expected from DR800 (usually it is at around very top rpms where it hits peak).

Torque graph looks totally correct rpm/peak wise.
Yes bluesman, there is a K&N filter in there but I don't know if the airbox has been modded. I'll have to have a look-see .

In any event, it was nice to know that the seller of my bike had done a good job; if he got the fuelling right, I think he probably got the rest of it right as well (nice job Richard ).
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