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Help Please . Tx270 Won't Start . . Weak Spark ?


zman92020
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My 98 GasGas was becoming hard to start the last few times I rode it , , and now I can't get it to run at all . . I appears to have a weak spark at the plug {very small, not at all what I expect it should be like} . . with the plug out [ no compression] and kicking it rapidly, I have a very weak spark . . hard to see at all but there is a slight one . Yep, tried a new plug . . same thing. I then pushed it down a steep hill and jumped it in 5th gear and no fire at all, no even a cough . . I'm sure one of you guy's have been through this before . . Will you give me some thoughts on where to start looking and how to test please ? How hot should the spark look . . when I open up the gap on the plug, there was no spark at all . . what gap should a good spark jump . . Thanks . .

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Take the plug cap off and test the H/T wire is producing a spark, may just be the cap itself. Expose a few wires and test the spark as you would a plug. If there is no spark it may be the ignition itself, had an ignition unit go on a 01 Gasser before but its either working or not, it wont produce a slight spark if knackered

Edited by Betarev3
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OK . . Here's what I found today . . I took off the spark plug boot[ this was a great place to start . . thanks for the tip] and had a hot spark from the bare wire to ground . . testing the boot found it has 4500 ohms resistance . . .then the bike had a resistor type plug from the previous owner . . it was about 5000 ohms . . so my question now is

1] is the boot suppose to be a resistance type and what is the purpose?

2] the bike was running fine for the past 6 months . . why did it all of a sudden stop starting . . ?

Thanks for the help . .

Dave

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The cap should have a resistor it is there to supress radio interference. I would guess the plug does not need to be a resistor type - should be easy enough to find out. The reason for the fault is probably the connection between the lead & cap deteriorating but I have also had problems with intermittent continuity in old plug caps. I would suggest buying a new NGK rubber type cap and the correct grade of plug.

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1st of all, thanks for the replies . . and here is what I found . . by having a resistor cap and a resistor pluk, the spark was deminished . . so I put on and straight non-resistor cap with a NGK BPR5ES plug . . . since I had the gas tank off while checking all the wiring, I squirted some gas in the spark plug hole before I replaced it, then kicked it over and it fired off for a second . . then stopped . . so I figure I've got it fixed, I replace the tank and seat/fender and roll it out of the garage . . .

Now here is where it gets real interesting, and where I learn another lesson in life . . .

It wont start again . . . same symptoms as in the begining . . . . I just saw it run so I know its got spark . . so I figure maybe there is a carb problem also . .and what the hell, let's pull the carb and take a look . . .

I go to take off the aire filter and the first thing I see is it is covered in dust and dirt . . Now I had just cleaned it and went for a 2 hour ride, but the place I went was dusty . . . seems just 2 housrs had sucked up enough dust to completely plug tyhe air filter . . even though it was running great when I finished riding before, it was too pluged to start . . seems like the blocked airfilter was acting like a giant 'choke' and flooding the engine . .

So there is the whole story, and I admit I was a 'bonehead' for not picking up on the air flow quicker . .

The moral of the story is that "in life when you don't get what you want, you get experience instead" . .

Edited by zman92020
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Good to hear you got it sorted out. Yes, those tiny filters don't stay clean very long if its running at trail speeds.

To make you feel better, I had a hell of a time getting my bike going one day during, and after a lot of off/on rain. It had always fired within a couple kicks and this day it would start, then stall, then bog when hard on the gas. I kicked so much my instep was hurting. The next day I thought it was time to clean the carb & filter, so I pulled the cover off and found the bottom of the filter submerged in water. Lesson learned .... pull the plug out of the bottom of the airbox after it rains (if you have one).

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