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The new BEAST has some issues UPDATE: getting there :)

Discussion in 'Technical and Troubleshooting Torque' started by slickncghia, Jun 16, 2008.

  1. G'day Guys,

    the new (yet to be named) beast is having some issues.

    For arguments sake lets just call it a suzuki dr 800 as thats what the engine/carbs are. (its a bit of a bitsa/Supremotard/xfr)

    originally the carbies were overflowing. however with a bit of fcuking around with the float levels and getting it all to sit straight i think i have stopped this (touch wood)

    however (and this was happening before i fixed the overflowing)

    it is suffering from what seems to be a fueling issue. it seems to really have a lack of top end (...yes,yes even more than a single should :p ).

    it is pulling roughly ok i think however it seems to have trouble getting to higher rpm. when on about 1/2 throttle in top gear it seems to putter along a bit however when the throttle is wound on even more it seems to struggle and surge as if its possibley going to stall. top speed atm is around 80ish (bike stock should do at least 170 on knobbies).

    looking at the carbies one of the afr screws seems to be wound all the way in(closed[lean]) and seems to be siezed in there.

    the (cant remember exsact name) jet needles maybe (the bit that gets pressed down by the floats) looked fine.

    Can anyone suggest things i should look for or anything that could be causing these issues?

    any help greatly appreciated.


    edit: it has also had the fuel pump and inline filter removed and is running gravity fed atm (Which apparently was running fine with for a while) it does also have an custom header 1 3/4 " and an aftermarket pipe. im not sure if the jetting has been changed im under the impression that they are the standard 33mm minks
  2. Your fueling problem may not have been level, but crap under the needle. So in lowering the float height you've leaned it out too much right across the range.

    If however you've the float level is right, then do a plug chop at full throttle and tell us what it's like.

    Oh and 170? :LOL: :LOL: :LOL:
  3. it was having the issues before the float height adjustment. it may well be lean though as the afr screw seems to be wound all the way in.

    also ive (hopefully) set the float height correctly.

    what exsactly do you mean a plug chop?

    yes 170...well its a big single ... i dont have enough points on my licence to go any more than that :p
  4. Find a desereted piece of road, get it in second or third gear and wind the throttle open. Hold it fully open for a couple of seconds, then kit the kill switch (and pull in the clutch).

    Now pull the spark plug out and see whether its sotty or white or clean. This will give you an idea of the size of your main jet.

    you can do the same thing at 1/4, 1/2 and 3/4 throttle to give you an idea of you needle jet setting. use a bent bobby pin and some masking tape to get the exact throttle position. You'll need to get the main jet right before it means anything however.
  5. ok ill have a look into that. cheers

    any other suggestions guys
  6. That was off the streetfigher forum yeah? Hmm, sounds like you've been lumped with a bit of a dog. Hope the price was right. Did the previous owner ever have it running properly?

    Your problem sounds similar to what happened when I pulled the ram-air system off my Ninja to get the fairings off it. Without the forced air induction, it performed woefully at freeway speeds, chopping in and out and generally struggling to maintain a speed on a constant throttle.

    I ended up hacking the airbox to fix it, running a direct link from the float bowl pressurisation tubes (which normally sit in the ram air stream) up through the bottom of the airbox and filter to the clean, filtered side of the airbox. This equalised the pressure between the airbox and the float bowls and the ZX9 now runs perfectly, although without the benefit of ram air.

    Now, it doesn't look to me like the DR has any sort of forced induction when stock:


    But my question would be: would the streetfighter conversion have made any significant mods to the air intakes or airbox?


    Seems like a pretty extreme kind of bike - an 800cc single... I can't help but think you've made life very difficult for yourself, buying a customised version of a rare bike that's not running properly and whose engine is well above the accepted maximum efficiency size for a single cylinder!
  7. hehe yeah i like to make things difficult dont i :p what can i say, i get bored when everything works all the time.

    the price in the end was ok i think, that will all depend on how much of a pain in the arse it is to get running right.

    apparently the previous owner had it running right, but i dont know how much credability that has.

    theres no forced induction (..yet :twisted: ) im thinking that its running lean. or possibley theres a blockage in the fuel tank filter.

    yeah i saw your probs on there, the only thing in the conversion that i think couldve affected it is the removed fuel pump and or different exhaust. everything else seems stockish.
  8. on it being too hard. luckily its a single :p

    assuming they are the stock carbies (havent actually checked the model number) they are MIKUNI BST33 which are luckily are also the same as the suzuki GS500 series and the dr350 and the aprilia pegaso 650. so carbie parts shouldnt be too hard to find.
  9. edited: disregard
  10. udpate: fcuk its good having someone who knows there shit giving advise.

    over flow still fixed :)

    so the main issue seemed to be that it was in fact running too rich. i did a test ride without the air filter (ie adding more air leaning it out) and it felt alot better. so i pulled the carbs out again and found that old-matey had #135 jets in there when they should run #120 stock :shock:

    so i whacked in some verry conveniently located #120's and it runs alot better. It will still need some fine tuning but i will sort that out with some plug chopping.

    its also crackling and popping a bit apon closing the throttle and the header pipe is glowing pretty red. which seems to indicate that the pilot circuit might be running lean (which makes sense with the afr screw seemingly all the way in and siezed) so i will try putting in a 1 size bigger pilot jet to richen this up a little

    so yeah, hopefully thats the main issue sorted :grin: and she's not a dog
  11. Idle circuits don't supply enough fuel to make exhausts glow red, you have fuel still burning in teh exhaust system or an ignition timing issue (unlikely)
    I suspect you have excess fuel being drawn into the engine, possibly float level too high or a vacuum diaphragm hanging up and leaving teh main jet drawing fuel. Does it surge when you brake hard?
    It could also be exhaust valve clearances are to tight, allowing the combustion process to continue in the exhaust.

    Regards, Andrew.