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brian
Joined: 22 Aug 2011 Posts: 3769 Location: Australia
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Posted: Sat May 03, 2014 1:05 pm Post subject: |
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SpikeC wrote: |
I installed a set of California Cycle Works "Exactfit" belts, they are highly regarded hereabouts. I have heard from one who should know that the Gates belts are not quite close enough for these motors.
Acquiring them where you are may be an issue, tho........ |
I can get a set of the Exactfit belts on ebay for about $125 aus _________________ '99 DB4 #104, '96 SB6 #1165, '94 DB2 J #652, '99 DB4 #088, '08 VTX1800, '93 ZXR750R M1, '95 ZXR750, '95 ZXR750 Race Bike, '94 CBR400rr NC29 Race Bike, '94 CB250, '49 BSA C10 250, '61 BSA A10 650, '89 ZXR750, '91 Ducati 851 |
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deebee4
Joined: 08 Jan 2011 Posts: 266 Location: Netherlands
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Posted: Sat May 03, 2014 10:27 pm Post subject: |
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brian wrote: |
Anybody ever experienced a dodgy CDI unit on a db2, 3 or carbed db4? I'm still having the same trouble with this db4, seems to foul the plugs and miss and fart and carry on.
I can get a good 2nd hand CDI fairly cheap so thought I might get it to at least eliminate that as a possible cause. |
You mean the Kokusan ignition boxes? Just switch them over and when the other cylinder runs bad this might be the case. Sometimes it happens.
I don't run the Kokusan CDI units anymore, I run the old Bosch BTZ CDI units. Did the mod around 8 years ago, never misfired again. Works great. But also replaced most of the wiring in the ignition circuit with heavy gauge wires, like 2,5 mm2. The method of elimination of possible causes just worked out well. _________________ Track riding on a Bimota: FUN! |
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brian
Joined: 22 Aug 2011 Posts: 3769 Location: Australia
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Posted: Sat May 10, 2014 8:29 am Post subject: |
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deebee4 wrote: |
brian wrote: |
Anybody ever experienced a dodgy CDI unit on a db2, 3 or carbed db4? I'm still having the same trouble with this db4, seems to foul the plugs and miss and fart and carry on.
I can get a good 2nd hand CDI fairly cheap so thought I might get it to at least eliminate that as a possible cause. |
You mean the Kokusan ignition boxes? Just switch them over and when the other cylinder runs bad this might be the case. Sometimes it happens.
I don't run the Kokusan CDI units anymore, I run the old Bosch BTZ CDI units. Did the mod around 8 years ago, never misfired again. Works great. But also replaced most of the wiring in the ignition circuit with heavy gauge wires, like 2,5 mm2. The method of elimination of possible causes just worked out well. |
Yes i think thats them. I didn't realize until i looked again today that there is one for each cylinder. I originally thought that there was only one. I'll try swapping them over to see what happens. _________________ '99 DB4 #104, '96 SB6 #1165, '94 DB2 J #652, '99 DB4 #088, '08 VTX1800, '93 ZXR750R M1, '95 ZXR750, '95 ZXR750 Race Bike, '94 CBR400rr NC29 Race Bike, '94 CB250, '49 BSA C10 250, '61 BSA A10 650, '89 ZXR750, '91 Ducati 851 |
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brian
Joined: 22 Aug 2011 Posts: 3769 Location: Australia
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Posted: Sat May 10, 2014 8:40 am Post subject: |
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Ok so i spent a little time on this again today.
I pulled the kill switch apart, cleaned up the contacts, put some gielectric grease on them and put it back together. It looked ok and i doubt this was the problem but at least can eliminate it now.
I've pulled the carbs out again and stripped them. The fuel bowl end looked clean and no blockages in any of the jets etc. The vacuum diaphram end was another matter. A heeap of crap under the diaprams, looks like dirt and sand! I have no idea how it has got in there, the filter looks clean and the inside of the airbox looks fairly clean other than some oily crud I'm guessing from the crankcase breather or maybe from backfiring. Again, not sure if this is even the problem as i haven't found any jets or passages blocked.
Can anyone help me with settings for these carbs? The needle clips are currently on the bottom groove and pilot screws are 2 3/4 turns out. Not sure what the float hieight is as i forgot to measure it today. _________________ '99 DB4 #104, '96 SB6 #1165, '94 DB2 J #652, '99 DB4 #088, '08 VTX1800, '93 ZXR750R M1, '95 ZXR750, '95 ZXR750 Race Bike, '94 CBR400rr NC29 Race Bike, '94 CB250, '49 BSA C10 250, '61 BSA A10 650, '89 ZXR750, '91 Ducati 851 |
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deebee4
Joined: 08 Jan 2011 Posts: 266 Location: Netherlands
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Posted: Sat May 10, 2014 8:58 am Post subject: |
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Hi Brian,
In the time when my db4 still had the Mikuni CV carbs I found a nice tune up instruction on adjusting these carbs inc the float height on the internet. I'll have to dig them up from somewhere.
You might even find it on the internet yourself by googling "mikuni BDST38" and with various search words like "tune up", "adjusting" , "float height", Ducati. Just try out various combinations and in the end you'll find the stuff you need.
I also have the Haynes Manual for the Duc 900ss that might cover the carbs too. I'll look into that but I can't promise I'll get back to you today, because of a busy schedule today.
Cheers! _________________ Track riding on a Bimota: FUN! |
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deebee4
Joined: 08 Jan 2011 Posts: 266 Location: Netherlands
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Posted: Sat May 10, 2014 8:58 am Post subject: |
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double _________________ Track riding on a Bimota: FUN!
Last edited by deebee4 on Sun May 11, 2014 1:41 pm; edited 1 time in total |
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2bims
Joined: 03 Apr 2010 Posts: 7289
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Posted: Sat May 10, 2014 9:38 am Post subject: |
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Haynes Manual for Ducati 900SS/SL models....Mikuni BDST38mm CV
has the following settings:-
Main Jet - 140
Main Air jet - 70
Needle Jet - Y-2
Jet Needle - 5C19 - 4th notch from top
Pilot Jet - 42.5
Pilot Air Jet 60/1.4
Unfortunately for the pilot jets it says check how many turns out it is, rememeber and reset to this...no number given |
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brian
Joined: 22 Aug 2011 Posts: 3769 Location: Australia
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Posted: Sun May 11, 2014 1:13 am Post subject: |
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Thanks for the replies deebee and 2bims. I recall going through this before and never really found definative settings. I previously got it to run 'ok' but never really ran 'right'.
I've heard that the neddles and emulsion tubes wear out on the carbs too, especially on ducati engines. So i might just buy a new set of carbs from that fella in Italy that you put me onto Steve. Hi s price has gone up 30 euros but still the cheapest i've found by far.
For the dirt/ sand to be under the vacuum diapragms, i guess it must have entered through or around the filter but i have no idea how? I'll post a pic of it, there was a lot of crap in there. _________________ '99 DB4 #104, '96 SB6 #1165, '94 DB2 J #652, '99 DB4 #088, '08 VTX1800, '93 ZXR750R M1, '95 ZXR750, '95 ZXR750 Race Bike, '94 CBR400rr NC29 Race Bike, '94 CB250, '49 BSA C10 250, '61 BSA A10 650, '89 ZXR750, '91 Ducati 851 |
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deebee4
Joined: 08 Jan 2011 Posts: 266 Location: Netherlands
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Posted: Sun May 11, 2014 10:56 am Post subject: |
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The needles and emulsion tubes are known to ware out on Ducati engines with high mileage. If they're worn you can see that the emulsion tubes ave become oval and you can see ware on the needles. If they look good they're not worn! Also these parts art available as spare parts! No need to spend a lot of money on complete carbs! That's a waste of money.
You might also fit the Dynojet Stage 1 or 2 needle/spring set, when you do have to replace the tubes/needles.
Where's the sand? On top of the membranes (under the plastic cover) or below? The 90º tubes protruding from the side should have a rubber tube on them, originally these run into a triangle shaped "container" fitted on the LH inside on the frame below the ignition coils.
I checked the set of BDST carbs I have still lying on the shelf, that came off my db4 when I replaced them with the 41mm FCR kit. It had the dynojet stage 2 kit fitted and would make a difference. Needles (steel instead of aluminium) are fine and tubes too. Willing to sell.
Also I found that float height adjustment info:
http://www.ducati.ms/forums/57-supersport/84326-float-adjustment-procedure.html
http://www.ducatisuite.com/jetkit.html
http://www.factorypro.com/prod_pages/prodd08.html (scroll down)
http://www.factorypro.com/Prod_Pages/prodd09.html _________________ Track riding on a Bimota: FUN!
Last edited by deebee4 on Sun May 11, 2014 11:44 am; edited 2 times in total |
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brian
Joined: 22 Aug 2011 Posts: 3769 Location: Australia
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Posted: Sun May 11, 2014 11:40 am Post subject: |
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The sand was under the diaphragms. The dynojet kit is a good idea I recon. What would you recommend, stage 1 or stage 2? Do you know if the dynojet kit comes with orings for the whole carb? _________________ '99 DB4 #104, '96 SB6 #1165, '94 DB2 J #652, '99 DB4 #088, '08 VTX1800, '93 ZXR750R M1, '95 ZXR750, '95 ZXR750 Race Bike, '94 CBR400rr NC29 Race Bike, '94 CB250, '49 BSA C10 250, '61 BSA A10 650, '89 ZXR750, '91 Ducati 851 |
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deebee4
Joined: 08 Jan 2011 Posts: 266 Location: Netherlands
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Posted: Sun May 11, 2014 11:52 am Post subject: |
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brian wrote: |
The sand was under the diaphragms. The dynojet kit is a good idea I recon. What would you recommend, stage 1 or stage 2? Do you know if the dynojet kit comes with orings for the whole carb? |
Hi Brian, see edited answer above. Dynojet Stage 1/2 sets comes with (lighter) springs, needle washers and needle clips.
Stage 1 is for Ducati's with stock air filter and exhaust system, stage 2 is for modified air filter (or pod filters) and modified exhaust system. I think Stage 1 would do, but Stage 2 would perform too on a db4, because its exhaust and airbox differs anyway from the Ducati's.
If you want a gasket set for the BDST38 just go to the Ducati dealers or the Yamaha dealers (TDM900 has the same carb setup) or just get 2 sets on eBay.
But you can buy my Mikuni set if you want. It worked fine when I replaced them with the FCR kit (that works better on a tuned engine anyway) _________________ Track riding on a Bimota: FUN! |
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brian
Joined: 22 Aug 2011 Posts: 3769 Location: Australia
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Posted: Mon May 12, 2014 9:03 am Post subject: |
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Thanks for the links to the info deebee, much appretiated!
I'll have a closer look at my needles and tubes tomorrow, but from memory i think they looked ok. Tis bike has about 22 000 klm on it so i wouldn't considder that high milage i guess.
I'll send you a pm.
Cheers,
Brian _________________ '99 DB4 #104, '96 SB6 #1165, '94 DB2 J #652, '99 DB4 #088, '08 VTX1800, '93 ZXR750R M1, '95 ZXR750, '95 ZXR750 Race Bike, '94 CBR400rr NC29 Race Bike, '94 CB250, '49 BSA C10 250, '61 BSA A10 650, '89 ZXR750, '91 Ducati 851 |
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brian
Joined: 22 Aug 2011 Posts: 3769 Location: Australia
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Posted: Tue Jun 17, 2014 1:09 pm Post subject: |
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Well I'm starting to feel a little hopeless with this thing.
I've put new seal kits in the carbs after giving them a thorough cleaning. Checked the needles and tubes again and they look fine. I set the floats to 14mm and the pilot screws to 2 3/4 turns out. Put it all back together and it wouldn't start. Put new plugs in and got it to run on one cylinder. The front cylinder just won't fire. It's getting plenty of spark, with the plug removed and earthed, it sparks like a beauty. There's definitely fuel in the carb bowl. Runs on the rear cylinder only, front header doesn't get hot.
I'm pretty sure that the carbs are put together right but I don't know what to do now other than pull the carbs out again and strip them again.
_________________ '99 DB4 #104, '96 SB6 #1165, '94 DB2 J #652, '99 DB4 #088, '08 VTX1800, '93 ZXR750R M1, '95 ZXR750, '95 ZXR750 Race Bike, '94 CBR400rr NC29 Race Bike, '94 CB250, '49 BSA C10 250, '61 BSA A10 650, '89 ZXR750, '91 Ducati 851 |
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brian
Joined: 22 Aug 2011 Posts: 3769 Location: Australia
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Posted: Tue Jun 17, 2014 1:23 pm Post subject: |
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Here's a weird thing... 3 weeks ago before I pulled the carbs out, I removed the front plug as it wasn't firing. When I got the plug out the porcelain top of the plug was broken. I thought I must have broken it with the plug socket as it was a bit awkward to get at it with the fairing on. Yesterday when the bike wouldn't start after fitting the carbs, I removed the plug lead from the rear plug and the top of the plug came off in the plug cap. The porcelain part broken. I couldn't have broken this one as I hadn't even put a plug socket on it as yet. I've never seen a broken plug in my life, now both plugs in this thing were broken??? May have been a dud set of plugs.
I'm nearly ready to throw the towel in _________________ '99 DB4 #104, '96 SB6 #1165, '94 DB2 J #652, '99 DB4 #088, '08 VTX1800, '93 ZXR750R M1, '95 ZXR750, '95 ZXR750 Race Bike, '94 CBR400rr NC29 Race Bike, '94 CB250, '49 BSA C10 250, '61 BSA A10 650, '89 ZXR750, '91 Ducati 851 |
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2bims
Joined: 03 Apr 2010 Posts: 7289
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Posted: Tue Jun 17, 2014 1:59 pm Post subject: |
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Try not to despair Brian....if you wanted an easy life then all your Bikes would be Hondas..and then you'd have no cause to spend all those happy hours in the stable of bikes.......and we all know that time in your man cave is allowed....but riding time is limited.
I'm surprised that for the sake of 85GBP you havent just picked up a whole new set of Mikuni 38's from that nice man I use in Italy....its what I bought for the pup I restored........plugged the twin cable throttle in...linked up to hoses...and first crank of the bike when fully constructed and the darn thing scared the life out of me by firing up first time.never touched any of the internals or anything...Can dig out the link to his site and the carbs again if you like...........?? |
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