Triumphrat

39032

i have a problem with my 885 carb model tiger 1995 starts and ticks over lovely sounds great but at top end splutters and misses this is annoying but what really hurts is that it is only doing about 20mpg carbs have been off and on several times now but think this is where the problem lies, it has a good second hand set of coils on it and a new air filter and new sparky plugs. im at end of tether and may just try to sell it on with this problem but dont think i can affrod the loss id make, anyone have any ideas where i should start looking on the carbs for this problem?


heeeeeelllllllllpppppppppp

if anyone is interested in this project let me know and make an offer im sure this is an easy fix for someone who knows what they are doing or has a bit of money to pay for it to be done

The Kurgan

Maybe there's a partial block in one of your fuel lines. Worth a check.

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Bixxer Bob

If the problem's top end it's main jet related. Your mpg suggests rich running (or a fuel leak) I would strip and inspect the needles and needle tubes, maybe buy recon kits? Also check the float levels and float valves. If they're leaking the float level won't make any difference and you'll be losing whatever leaks down the overflow pipes.

miker

Bixxer is on the right track, but you say there are second hand bits in there as well.

First things first. You need a good workshop manual.

Make sure the electricals are all correct. Good coils, good high tension leads and good plugs. Make sure the ignition timing is correct! You can't do anything with carbs until the spark is in perfect condition. Your second handy coils could be second hand for a reason.

Take the carbs off the bike, clean them, replace the needle jets, double check the needles are in the right place. Take the floats out and check for leaks, make sure they're all floating as they should and that the float level is absolutely spot on. Unscrew the main and the primary jets, make sure they're clean and then blow out the jet seats. Also a good idea to check what size jets are in there, compared to stock. Sometimes people put bigger jets in thinking it will go faster, when in fact it's usually a waste of time unless you have a cam and other "enhancements".

Put the carbs back together carefully, take your time and make sure they're all correct. Before you put them back on the bike, carefully inspect the manifold faces, the manifold rubber and any other connection to the bike. Carefully inspect the air cleaner connection as well.

Set the idle/air mixture per the book before you start it, then get it going and balance the carbs correctly.

Rule number one. Start at stock and work from there, taking it one step at a time.

Rule number two. Patience

I sometimes wish I had carbies to play with, instead of being a **** to the dealer with an ECU.....

Mick

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Bixxer Bob

:

Gold star advice!!!

39032

Thanks Miker coils are good and ht leads good too, spark plugs are new and spark is good. just have few questions cos this is the last time im gonna attempt to fix this carb problem before she gets scrapped. i think it may be possible the jets in the second hand carbs are a different size or maybe not there! i didnt check just fitted them. its pretty obvious its overfueling using too much on mpg and exhaust smells very fuelly. the bike flies low down but top end misses. also if you brake hard and front end dips it floods and tries to stall?? could tis be main jet or possibly float valve ? i'm gonna buy new main jets new o rings and new air inlet rubbers do you think thats all i need or more . advice much appreciated thanks

39032

right i have taken apart one of the spare carbs as a dry run and to check what i need this is my parts list

pilot screw o ring
piston guide o ring
float assembly o rings
float chamber seal
vacum take off o ring
air inlet manifold rubbers
main jets
jet needle

is this about right for what i would need? should i replace the needle jet too?

i took apart one of the carbs from the set i bought second hand and one from the originals on the bike the main jets are the same type but may just be my eyes but im sure the second hand one loos like its orifice is bigger maybe worn? so thats why going for new jets float valve height was low i think im right in saying this would provide a lesser amount of fuel than is required (it was 13.25mm) O rings in the second hand carbs were for want of a better word F***ed and the pilot screw setting was 3 and a half turns !!! stock says 1 and a half.

comments welcome thanks

Bixxer Bob

Pilot screw only affects tickover and very bottom end, but you say she runs ok in that area.

Dried up o rings will let air in uncontrolled and fuel out depending on which one of course. My guess is that someone opened out the main jet thinking it would go faster not realising they are precision drilled. By the way, they'll have a number stamped on them which should correspond to the recommended jet size in the manual. Start with new jets stock size as yours seem to be unknowns.

Just to be sure I'm not talking *oll***s I just dug my old Mikuni manual out of the garage. The pilot is tickover to about 1/4 throttle, needle 1/4 - 1/2 and main jet 1/2 - full.

39032

thanks bixxer sounds like it may be main jet as its over half throttle it plays up all o rings are f***ed float valve is not steady and bobbles about. im ordering from triumph so they should be correct jets, she ran perfect and did 180 miles to a tank before carbs were changed so sure the overhaul will get her back to this still not sure why she dies when bike is braked heavy???????

Bixxer Bob

I'm not familiar with the layout of your carbs, but you said the float level was low? Could be, under braking, the fuel is rushing to the front of the float bowl and falling below the pickup point so the carbs feed air instead of fuel. Only a guess....