hi, im new to the forum but have been browsing it for a while and im glad ive finally gotten round to registering
im having abit of trouble with our 34L, it has always been a bugger to start but would like to try and sort it before i have it on the road.
have just got a thin walled 18mm spark plug socket so have finally been able to remove the spark plug (not sure why yamaha have made it soo hard to access) which while removing i realised it wasnt tightened up fully, which i assumed was a contributing factor to the starting problems.
the plug was very coked up and was replaced.
the carb has been stripped/cleaned and rebuilt.
the valve clearances have been set (when first checked there was no freeplay in any rockers at TDC)
and the decompression cable has been adjusted correctly.
the only other thing i can think may be contributing is the battery needs a good charge but my charger has suddenly decided to konk out :/
once its running it runs really well so im at abit of a loss, if anyone has any theorys/experience i would be very gratefull.
cheers,
Higgins.

What year model is your 600? Is it electric start? Do you have any backfire issues?

If you are kick starting, and you probably are since you mentioned the decompression cable. Are you following the recommended start procedure?

No throttle, little if any choke if it is warm weather. Kick starter down slowly until you hear a click. Allow to return then wail on the kick start. Only add throttle if you hear it fire and start.

Some problem areas are air leaks in the intake boots carb to head. They get hard and leak, this causes a lean mixture.

As Mezo said, check the stator winding, trigger coils (there are two) and see how they compare to the manual specs. If you don't have a manual, ask here and someone can give you the color coded wires and the OHM's value to expect.

I have found that also checking the AC voltage output of the stator coils and trigger coils is helpful as well. Exhaust the stator checks throughly. Another trouble area can be the system ground. The black ground wire is close to the coil. Some have found the ground wire inside the harness to be broken so no frame ground.

Do you have a side stand switch? If not, don't worry about it, if so, trace the wire upwards and find the bullet connectors where it plugs into the main harness. unplug it and plug the harness side bullets together to bypass a potential defective sidestand switch.

This is lot to check but will give you a kind of checklist to go by. If your bike is the older style with CDI ignition then the battery is not part of the ignition at all, the stator supplies the power to the CDI.

Fill us in and we'll try and help you.

Steve

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'84 XT600 is now bored to 2nd oversize and new OEM pistons and rings installed. No more smoking.

hi thanks for the quick replies its really helped. ive got the stator and ignition coil off the bike and warmed them up before testing the resistances
the pickup coil should read 90-129ohms but im reading 252ohms
the source coil should read 160-240ohms and im getting 208ohms
the ignition coil should read
0.27-0.33ohms for the primary coil but im reading 1.5ohms
3.44-5.16K ohms for the sec coil but im getting 16.39K ohms!

so am i right in thinking my source coil is all good and its the pickup and ignition coils that are the problem?

many thanks for all your help,
Higgins.

have just had the stator of one of our 2 55W's and again the source coil reads ok at 199ohms but the pick up coil is reading 242ohms :/ seems this may be a common fault

You are probably using a Clymer manual. The pins they tell you to read is across both of the trigger coils in series. Measure between each of the ones you are now measuring but the other lead to the unmentioned wire. Do this for each pair and you will see 1/2 the reading. The OEM Yamaha manual has it right. This is just one of many faults with a CLYMER manual.

Mezo told me you have a first model Tenere and I figure it will be just like the older XT's. I measured my 84 and 86 stator coils as follows:
84 pickup coil per Clymer 236.0
86 pickup coil per Clymer 229.5
84 Source coil 205.7
86 Source coil 205.9

84 coil primary .7 ohm
86 coil primary .7 ohm

84 secondary w cap 18.4k with out cap 6.6k
86 secondary w cap 17.8k with out cap 6.4k
The spark plug cap has a 10k approx. resistor as you can see above, much less measured without the cap.

If you cut the pickup coil values above in half, it falls within spec. I did go back and measure again and it did measure in spec on both trigger coils. You'll see the same thing.

Your primary coil winding is about twice mine and "COULD" be suspect. If you can borrow a coil and test do so.

I was in the same boat as you except after sitting for several months while I fixed oil leaks, set valves etc. The 86 would NOT fire at all where it did run before, although it was hard to start and ran terrible.
My 84 has not run at all, I purchased it many years ago as a parts bike but never stripped it. It is very complete so I decided to get it running. It had the same "NO SPARK" problem so was no help in getting the 86 running.

I took a chance and ordered 2 Hyperpaks CDI's from New Zealand. After a very long wait, they came. I plugged them in and started the 86 pretty easily. The 84 has low compression so I did not try and start it but it does have spark with the new CDI.

I won't bore you but I now have a Zeeltronic CDI that works great and sold the extra Hyperpak. The purchaser of that unit solved his no start problem with the new CDI.

I suspect you have the same problem but do not want to recommend you purchase a CDI until you have exhausted my recommendations. If you need more info on the Zeeltronic, go to their website: http://www.zeeltronic.com and send an email to Borut, the owner. He can give you delivery time and costs. He is very prompt and a pleasure to deal with in Slovenia.

There are posts on here and the ADV forum where you can find out more about the Zeeltronic and the more low end power it produces.

Steve

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'84 XT600 is now bored to 2nd oversize and new OEM pistons and rings installed. No more smoking.

thats brilliant thanks for that i was beginning to get scared, tested the pickups of all 3 of our XT's and they were all reading the same but thats cleared alot up i went through the 3 ignition coils we have and found the best one (0.7ohm primary)and have fitted all back onto the bike and still no luck on the first few kicks the neutral light barley lights up and then gets brighter every kick, and after 10/20mins of kicking it sounds like it wants to fire up, which usually if i keep going it does but didnt seem like much point seeing as there hasnt been any improvement. i will be buying a new battery ASAP but im assuming it wont make a massive difference to the starting problem so on to the CDI i guess :/ i have 2 more CDI units that i can test fit, is there a way to test the CDI unit?

great news swapped the CDI with one off of the 55W's and she started on 4th kick i am a very happy chappy thank you very much for the info

ah brilliant cheers, weve got 2 more XT's and at least 1 faulty CDI so that'll def come in handy, and 6 months warranty seems like a good deal

Happy you found the problem. Did you go ahead and test the coils with the higher ohm values? It would be interesting to see how it compares with the .7 ohm one and like I said both of mine read .7 ohms.

These old CDI's can and do go bad. Nice you have a spare to try out.

Steve

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'84 XT600 is now bored to 2nd oversize and new OEM pistons and rings installed. No more smoking.

ye i did the other two read...

primary-1.5ohms
secondary-15.89Kohms

primary-1.0ohms
secondary-34.2Kohms

strange that the second one reads less on the primary coil than the 1st but more than double the reading on the sec coil :/

the 1st coil is off an 83 34L and the second is from an 85 55W