engine will only start with starting fluid -runs- then dies

estewart · Full Member Joined: Dec 10, 2008 Posts: 28

i just rewired my bike after a rebuild (everything except the motor itself) new wires and the sale tci and regulator. i finally got it to start tonight. at first i was having trouble and tested the pickup coil. its suposed to be at 700 ohms, mine read at 700, 710, and 1650 ohms, so thats bad. i tested my ignition coil, primary checked out fine but the secondary is 11000 ohms over spec, so thats bad also.

i ordered a new ignition coil and waiting for specs on a pickup coil off ebay, but i looked through my repair book and noticed a wire that i grounded when it wasnt supposed to be Embarassed

, so i fixed it, kick started it and got some popping backfire, sprayed starter fluid in the carbs and gave it another kisk, it came to life and ran great untill it ate up the starting fluid, kept doing it to get a vacume in the carbs and tinkered with the idle and air/fuel screw... but no joy.

i know the ignition coil will need to be replaced, and i'm thinking i will be ok not getting the pickup coil because it runs great (when it runs)

so whats your opinion, should i replace both or just the ignition coil and what are other tips you guys can think of?

jayel

clean the choke/pilot jets and pilot jet circuits in the carbs, if it won't run except with starter fluid (very hard on a engine BTW) since it washes the cylinder walls and is a explosive mixture its got more than ignition troubles

royfisk

Amen jayel; If its running on scrap a engine and not on gassoline then more then likely you have carburation issues, but keep useing that stuff and a top end will surly be in your future.

estewart · Full Member Joined: Dec 10, 2008 Posts: 28

ok, thanks, i'll take them off today and see what i can do.

estewart · Full Member Joined: Dec 10, 2008 Posts: 28

so i cleaned the carbs out with break clean. (i dont have an air compressor) put em back on, and about 8 kicks later and one final use of starting fluid it now starts Smile

now ive got to do the next fun thing on the list... tweak the carbs, cuz when i go to give it throttle it will just cut out and die. also when i was able to get it going and got on the throttle it would seem to bogg down for a bit then backfire with a pop and then take off. so i think its running way too lean. so i'll play with it tomorrow and do the classic spark plug check.

but hey, at least its running.

blackwidow

Good deal glad to hear you got it running

xsjohn

BS34.......Did you remove the needle jets ......the brass part that the main jet screws into...they are removed by loosening the main jets and tapping inward......then they come out through the throat of the carb......if not cleaned and they were dirty it won't take the throtle .........and run like you described above.....

xsjohn

estewart · Full Member Joined: Dec 10, 2008 Posts: 28

XSJOHN- i removed the air/fuel screw, the diaphram and needle, the main jets and the float system. are you talking about the guide that the needle slides into? cuz when i took the diaphams out i sprayed directly into where the needle would slide into, but i can take a look. and you said to tap them inward, you mean up into where the butterfly valve is?

xsjohn

If the needle jets are dirty.....then it won't take the throttle...lean...if the carbs sat with fuel in them that had to be cleaned out of the bowls they are most likely nasty......

And yes it is the brass part that the needles slide into..

If the bowls were clean when you took the carbs apart then maybe they are ok.....but there is really only one way to find out and that is to remove and clean them......and the tiny holes on the sides of them...a q-tip shaft works decent throught the jet....and guitar string for the little holes...

and there is a starter jet in the float bowl that plugs causing hard starts.........

....xsjohn

estewart · Full Member Joined: Dec 10, 2008 Posts: 28

ok, there was fuel sitting in them for a while but when i took the carbs appart they were pretty clean inside, but being a newbie to carbs and all that i'll take your word for it and check them out. better to be safe than sorry.

and regards to the starter jet, i'm not having any issue with hard starts. since i got it going its been 1 maybe 2 kicks. and ive still yet to replace my ignition coil with 22,000 ohms resistance. so that will help out a lot when i get it installed.

xsjohn

If it fails to start easily and fast idol and run after starting then the starter jet in the bowl is plugged....sounds like you are ok there.........my concern is that it won't take the throttle correctly.....try setting the mix screws at 3 turns......the pilots jets are small in those from the factory..42.5...and it is winter that makes the mixes even leaner.....make sure it is warmed before you rev it.....especially with the very lean stock epa parts in them.......half choke may required until the engine nears operating temperature and richens a bit........

Hate to send you back in to check the needle jet but if there was no hardened fuel in the bowl.....then maybe just running it for a while might be what it wants..fuel is a penetrant and a cleaner of sorts.....hope this helps.....lean BS34's can be fussy....drove me nuts for years till I figured them....I can make those right for you later once you get them half decently panned.......and the timing on the tci bikes is a bit advanced......

xsjohn

blackwidow

I learned some important things in this topic

xsjohn

Don't give up on your BS34's...properly staged and jetted they are the best carb for the xs.......they can be set to run right and deliver good gas mileage at the same time.......on my Ole 8-1 I get 54 mpg with the next hotter plugs that run a nice grey at any speed with a lot less vibrations....... took me a while to figure these cabs while everyone was talking them down.........all three stages have to be corrected properly before they shine........and they will.....always remember that the tci's are a bit advanced and the timing can be dialed in.....and last summer I added some fins to my 8-1 to better direct the air flow to lower the cylinder temps even farther..........runs at a nice 230 max cylinder temps now at 90 degrees on the express at 65-70.......down from 280 10 years ago from day one....getting one exit with stock settings was a Holocaust then.......not any more .......temps hose everything including the riding fun....and the stock 80-84 compression is a bit high for sustained highway riding for the long run.....for sure........

And for those who still have no clue to the thrashing thing below you ...it's gearing...compression and carbs and a bit of study on engine longivity......but you will find out......for sure...and there will be no main bearings left once you figure that one.... for sure....wife says I need to work some more on longivity myself so....guess I need to tend to other things........... Shocked

xsjohn

danno · Full Member Joined: Mar 04, 2006 Posts: 212

John,do you make needles for the38s,too? Maybe the 38s are good as is?

estewart · Full Member Joined: Dec 10, 2008 Posts: 28

yeah i learned quite a bit on this topic. some of what you said was a bit over my head but it will eventually click and all make sence.

but thanks to all that helped out. i appreciate it.

jayel

the old saying that you have to clean the carbs three times applies Laughing

there are three small holes in the front of the carb throat that have to be clear, remove the air idle screw and shoot carb cleaner using the plastic tube into the air idle hole it should come out those three holes, cover the holes with your finger and the spray should come out the passage leading to the jet (watch your eyes) you don't need them cleaned with carb spray

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