Bimota Forum

[bimotanige]

chaps
any ideas what's causing this brown deposit on the engine side of the CV carbs on my KB1. It started running rough and then only revs if the choke is on full. the deposit doesn't seem to be dissolved by petrol or cleaner - it takes T cut to clean it off as it is really sticky like tar? Plugs are light brown, compression seems good, it's run ok up to press.
the rough running may be the sticky stuff is stopping the butterflies opening easily?


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KB1x2, SB3 SB4 BB1 DB2 Vdue Evo YB11 RB1 Ducati MHR Suzi GS650

[2bims]

Sticky brown treacly sweet stuff....sounds like high ethanol additions to fuel...you still filling up at Tescos and Asda?....Only 97 grade for me and never at Texaco or shell as they add ethanol to all grades (Which can come from Sugar Beet)....What tanks on the KB1? Ally or Plastic? Is there a liner in it thats degrading or high deposits in it?

[brian]

Only runs with choke on, sounds like a blockage in the pilot circuit to me. That sediment or sludge may have blocked a pilot jet or two. Very tiny holes in the pilot jets. I'd give the carbs a good clean and put fresh fuel in t.
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'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

[mad mundy]

Dude ok if that was fuel deposit who ever is selling it would be sued out of bizness. It ain't fuel. Looking into my crystal ball it seems to me that it is oil.
Two things, never assume your compression is "ok" & does it use oil ?
If so start at the pugs,are they the same colour. Is there a crankcase hose to the air box ? Kooz that shit is either getting pushed up the inlet tract or pushed thru the air filter, I think the later. Find a Yamaha shop & order the carburettor cleaner, this stuff is evil but works. One must treat that shit with the respect you give the sea.
Needs a re-ring.
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if you aint` slidn` , you aint` ridn`

[bimotanige]

Its the Z100 engine in the KB1. So far it hasn't used any oil since filling up. No hose from the crankcase breather as it vents out the back of the bike - no oil out of that. Plugs all same colour - light brown and clean. Looking down the bores I cant see any scoring or damage. Air filters are new. Suspect that its blocked jets in the carbs as per Brian.
I think its a case of cleaning the carbs and taking the head off for a peek Ive never seen anything like it as its only on the engine side of the butterfly valves
-agree with Mr mad that its an oil/ contaminant deposit
will keep you updated
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KB1x2, SB3 SB4 BB1 DB2 Vdue Evo YB11 RB1 Ducati MHR Suzi GS650

[Evilchicken0]

If it's only on the engine side of the butterflies then it might be oil but it could be something like a plastic / rubber part getting part dissolved, a gasket ... maybe the petrol cap or fuel tap seal.

Clean the carbs - obviously, then run the bike up with new fuel in a different tank.
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Don't read everything you believe

[bimotanige]

Hmm I'll have a good look in the tank. I emptied it when I got the bike but as the tyres were dated 1994 and still had the bobbles on them in the middle it had obviously not gone any distance. It may have had a build up or foreign object in it over the years. However I've done about 700 miles since rebuild with new fuel plus additive. Nothing obvious in the float bowls either.
Keep the suggestions coming - all greatly received
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KB1x2, SB3 SB4 BB1 DB2 Vdue Evo YB11 RB1 Ducati MHR Suzi GS650

[bimotanige]

Hmm I'll have a good look in the tank. I emptied it when I got the bike but as the tyres were dated 1994 and still had the bobbles on them in the middle it had obviously not gone any distance. It may have had a build up or foreign object in it over the years. However I've done about 700 miles since rebuild with new fuel plus additive. Nothing obvious in the float bowls either.
Keep the suggestions coming - all greatly received
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KB1x2, SB3 SB4 BB1 DB2 Vdue Evo YB11 RB1 Ducati MHR Suzi GS650

[851jim]

Hi Nige
Bought an 851 around twenty years ago, had exactly the same problem, jammed the injectors, clogged the pump filter and really sticky inside the tank. No one could explain what it might be, only way to clean the inside of the tank was with Methanol.

[Evilchicken0]

I used chew that methanol gum at raves
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Don't read everything you believe

[mad mundy]

Ether is so much more convincing ....so when was the engine last run & did it have a long rest before that
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if you aint` slidn` , you aint` ridn`

[bimotanige]

aha, I'll try the old model car fuel as that's methanol and see if that works and report back cheers Jim
Hi Mad
I don't think the bike had been run at all for 20 years to be honest. My plan was for an engine strip this winter as Im doing the closed road parade at the Manx GP next month on it. The bike only had a tacho on it when I bought it, but has been tuned as it is much quicker than my Z1000 I had, and I can see it has non original base and head gaskets. I did a basic service and double changed the oil after 250 miles. As per JRH I think it may have been dissolved coating/gunge in the tank as the tank looks very much cleaner inside than when I got it!!!
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KB1x2, SB3 SB4 BB1 DB2 Vdue Evo YB11 RB1 Ducati MHR Suzi GS650

[Evilchicken0]

Maybe it had some old fuel / oil in the tank - I do this if I want to store a tank or post it. I use engine oil with a bit of petrol and tumble the tank to coat the inside. It could be that coating dries out a bit over time then add in some ptrol and it washes it all clean but drops down through the carbs.

Clean the tank, petcock, fuel lines ect and it should be ok.
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Don't read everything you believe

[ct981]

On KB1
the inner tank should be aluminium and would be nice and shiney.
If there is any staining that would be removed by the fuel.
This residue would be taken through the carbs.

It may be a good idea to try and clean out the tank prior to next use.
Also use a good fuel filter.

Lastly I saw in a previous post you mentioned a breather, you must make sure that it is the tall casing with the spout directly under the frame.
If you use the low profile gpz style you will get issues.

good luck nice to see another KB1

[851jim]

Hi Nige
Careful with the model fuel, some have castor oil in the mix but any 'good'
model shop should be able to sell you straight methanol.
As for inhalation I think Amyl Nitrate probably worked better.