QuestionQUESTION: I have a 1972 Triumph Tiger that is fouling plugs (black soot) after a 1/2 mile and dying. After replacing the plugs the bike sometimes won't start (sometimes it does, but immediately fouls the plugs again). My mechanic, who is unfortunately 500 miles away, told me it sounds like an electrical problem and to get a test light and and trace from the spark plugs back to the battery. I am NOT a mechanic and have no idea even where to start. Is there some kind of guide or book to help me figure out how to isolate the problem and fix it. Thanks for your time, John
ANSWER: John,
You can have one of three problems...the first two are the most prominent. The carb float is not doing its job and letting raw fuel into the engine and fouling your plugs....you should smell the raw fuel or see it dripping from around your tickler button or running out of the air boxes...also check and make sure that your choke is not on...they pull off...the relaxed position is on...Ive had a lot of customers get this confused as it is the exact opposite on jap bikes. Next issue is points. If they are corroded or heavily worn they will offer a weak spark and cause poor combustion...but as your bike will dump a set of plugs in a half a mile , I am still leaning towards fuel...
How long have you owned this bike and when did this problem start?
You can order a service manual ...I can get them for you or you can usually find them on ebay.
Hope this helps
Deron
---------- FOLLOW-UP ----------
QUESTION: Hey Deron, Thanks so much for taking the time. Here's the deal: I recently purchased the 72 Tiger 650. I immediately brought it to a great Brit mechanic who is located several hundred miles from my town and he basically went through the bike. He put on a used 930 carb, changed a bunch of gaskets, plugs, o-rings, etc... When I picked it up, it ran fine at the shop. He warned me that the plugs could foul until it broke in a bit and advised me to carry an extra set. I trailered the bike home, fired it up and it literally went 3 miles and died. I changed the plugs and it fired right up again and then died shortly after. I noticed the hard-wired headlight was dim, so I tested the battery and ended up buying a new one. It fired right up and literally went 1/2 mile and quit (plugs were sooty black again). To your point, I have noticed that the prime pump on the 930 carb sometimes sticks and drips gas. Beyond that, I haven't noticed anything leaking from the carb. By phone, my mechanic thinks its still an elecrtical problem, but would that foul plugs like I'm seeing? What do you think my next step should be? Should I try to find a new carb, take the one I have and rebuild it, set the whole mess on fire and ride the bus?? Thanks brother for your time, John
AnswerJohn,
Plugs dont "foul until the bike gets broken in"...if the engine is tight and correct and the carb and timing is correct , the engine should run "as new" and not foul plugs. We are going to have to start with the basics and work our way out from there. This will probably take a while and I may ask you some stupid questions , but please keep in mind that I cant ride your bike , so that complicates things for me just a little..lol
First is a compression test...should be a minimum of 125 lbs per cylinder , but would be nicer if it was in the 140-145 range...the main thing is that the two cylinders are consistent with each other...this tells us if the basic engine is in acceptable shape to work with..I know you said that the bike ran good at the shop, but did you ride it more than three miles to test?
Number 2...pull your carb off the bike and take it apart... to get seperated from the cable, take out the two phillips screws and slide out the whole thing(slide and all). when you take the float bowl off, hold the carb upright or the float and needle will fall out on the ground and you'll be pissed..lol
check to see that the brass main jet is a 230. the number is stamped on the side..make sure that the tubular block/body that the jet is screwed into is tight...they will loosen with vibration it they were not properly installed....
If all looks good then reassemble the body and set it off to the side for now... Hanging from your cable is your slide assembly...pull up the big spring and hold it out of the way and slide the needle and clip up out of the slide...make sure that the clip is in the center of the three available slots.....if all is good then put it back together....when you slide the slide assy back into the top of the carb body , be sure to reach your fingers in and guide the needle down into the center main jet hole...they like to cock off to one side and cause a problem...
Let me know what you find and how you make out and we'll see if we can save you from having to ride the bus..
Deron
