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Discussion Starter · #1 ·
I have purchased a 90s softtail with a Revtech 125 installed, and Twin Tec ignition Model 1005.

It is a pain to start when cold (after sitting for a week or more). Usually I will completely flatten a battery trying to start it, and then it usually starts once the battery is recharged a few hours later after a lot more cranking.
If I pull out a plug I can see it sparking, I can smell fuel, it just doesnt go bang. I have tried combinations of choke and no choke, using throttle or leaving it alone, I haven't found a combination that works.

Although it probably doesn't explain it starting eventually, I wondered if the timing settings were less than ideal for the engine. It has a Twin Tec ignition Model 1005 with the following settings:

Motor vehicle Automotive lighting Font Gas Measuring instrument


Looking at the manual: https://www.vtwinmfg.com/Instructions/32/32-1005.pdf

It recommends using Mode Select of 7 for a High Compression engine, but am unsure if the RevTech 125 is considered high compression, and during start it has decompression plugs anyway, so I wouldn't expect this to be causing the issue.

Has anyone got a Revtech with one of these TwinTec ignitions? What settings do you use?

If it is not the ignition timing, what should I look at next? I am thinking perhaps air intake leaks.There is nothing obviously loose or leaking, but would be a matter of disassembly and putting it all back together.

Once it is running it runs well, and starts easily once it is used, but getting it started is a dog.
 

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My 1991 FLHTP was hard to start. I would pull my plugs after trying unsuccessfully and they would always be wet. I put new plugs in that were one heat range hotter and that fixed my problem.
 

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Discussion Starter · #3 ·
My 1991 FLHTP was hard to start. I would pull my plugs after trying unsuccessfully and they would always be wet. I put new plugs in that were one heat range hotter and that fixed my problem.
Cheers, I looked closer at the RevTech manual and it does give a recommended plug, so I will get them tomorrow and give a try: Autolite 4265 (set gap to .040" / 1.02mm)
 

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Sorry. I posted about this topic in your other post. It was about using the accelerator pump to assist in starting. Another point which might have something to do with starting is the type and age of your choke cable. I use the Harley friction cable on mine. They seem to wear out after 2-3-4 years and won't stay on when I start the paint shaker. I had the same issue when I was using the Mikuni detent type cable. When the bike starts running, the cable would not hold the handle out and then you don't have the use of the enricher circuit.

I have manual compression releases on mine and I never use them cold. It will just turn over. Once it has enough heat built up to run without the choke, I will use them every time. Until it has sat for a couple of hours, then it is a judgement call. Mine bike is only 95 inches, but I do have S.E. high compression pistons. Those with the 585G cams give me about 205 ccp. Sort of high.
 

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Check the compression first. Next check for nice fat orange spark at the plugs by cranking it over plugs out bodies grounded. All good, check static timing, the Revtech, if that what it is, should have a timing window and the DTT has instructions to check the static timing, light on at trigger point IIRC. If the plugs are fouled it won't start with everything else right.
 

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Discussion Starter · #7 ·
Thanks for the input. It cranks well.
Tonight I pulled out the plugs, cleaned and gapped to the manual spec.
I rerouted the fuel line which was taking an odd path, and put more fuel in the tank to get more flow.
It started well after a couple of cranks.
I suspect the plugs were not helping. About to add to my other post though, as still not sure what this engine is.
 

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Just to add more to my original post above. I pulled my plugs and cleaned and gapped them multiple times but it would only last a short time until the starting issues returned. Went to the new hotter plugs and the problem has not returned.
 
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