Question about Harley Davidson Motorcycles

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My 1985 evo is running very rough at low revs but is fine on the open road, in traffic its jerky etc, also its hard to start when its hot, its fitted with a harley cv carb, thanks Ray

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  • Jonathan Gallart
    Jonathan Gallart Apr 24, 2017

    Some times the Temperature sensor is involved on it, try check or replace, another sensor as the VOES in some models con be doing some bad connection or can have a damage.
    Cheers from Oaxaca, M?xico.

  • ray mc cormack
    ray mc cormack Apr 24, 2017

    Thanks for the advice Jonathan

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  • Harley Davidson Master
  • 41,657 Answers

Hi, Ray and the usual suspects are:
1. Severely discharged or a damaged battery, should have 12.5 volts or better and be able to pass a load test if necessary.
2. Check battery terminals for damage or corrosion, check the battery cables at "BOTH" ends for loose, corroded, or broken connectors, "INSIDE" and outside the cable harness, perform connector wiggle test and check cables with an ohmmeter if necessary.
3. Spark plugs in bad condition or partially fouled.
4. Spark plug cables in bad condition and leaking check for spark leakage in the dark
5. Spark plug gap too close or too wide.
6. Faulty ignition coil, module, and or sensor.
7. Loose, dirty, or corroded ignition module connector at crankcase.
8. Faulty CKP or CMP, MAP, ETS, ATS, TPS, O2 sensor.
9. Dirty air filter.
10. Intake air leak.
11. Water, dirt, or rust in the fuel system.
12. Carburetor damaged, contaminated, sticky float, plugged jets.
13. Multiple carburetors out of sync.
14. Fuel filter clogged.
15. Old or contaminated fuel.
16. Fuel tank vent system plugged or carb vent line closed off.
17. Gas cap diaphragm valve faulty.
18. Vacuum line from intake manifold to fuel valve is broken, cracked, pinched, or missing.
19. Carburetor controls misadjusted.
20. Incorrect valve timing.
21. Valve springs floating, weak, or broken.
22. Damaged intake or exhaust valve.
23. Incompatible performance parts.
24. Control module may be in "LIMP" mode
25. Check for engine trouble codes.
For more information about your issue and valuable "FREE" downloads that you will need please click on the blue links below and for more specific information or questions at no charge please feel free to contact me at xlch@mail.com. Good luck and have a wonderful day.
Out of nowhere Evo starts and runs rough Harley Davidson Forums
Harley Davidson Manuals Mark Workshop
http://partsfinder.onlinemicrofiche.com/ronnies/showmodel.asp?make=hdmc
Instant Tech Relief To speak with me personally absolutely "FREE"

Posted on Apr 24, 2017

Testimonial: "Hi Gregg, thats a lot to check, thanks"

  • Gregg Mahin
    Gregg Mahin Apr 24, 2017

    Ya I know but anyone of those will cause your issue have to be through

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Car has started give spluters when taking off from low revs but of at higher reves


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Its a hot start issue.

Can be related to low fuel pressure or problem with crank sensor.


Also it can be weak battery or starter.


But possibilities are to be inspected to confirm what exactly it is.------


To troubleshoot and confirm the issue,i suggest you refer few solved help links with similar types of problem like yours:------


Click the link below:------


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http://whatisbyme.blogspot.in/2012/05/1991-toyota-trecel-engine-starts-fine.html

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These details will help.

Thanks.

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1 Answer

Hyosung avitar 650 wont stay running


Maybe this will help. This is a common problem that I have had with my GV250. Almost the same bike mechanically by Hyosung.

If the battery is low on charge and you are lucky enough for the bike to start. As per normal when first started it revs higher because the bike is cold, this turns the alternator fast to give you the electricity you need to keep the bikes computer working properly. Bike will warm up and revs drop down, alternater not turning as fast, not as much electricity being made. Bike will either stall or rev up and down irradically to try to produce its own electricity. This will occur when the battery charge is low and bike is at low revs, for example when you slow down for traffic or you stop.

If this is your problem. To resolve it when you are out on the road, keep the revs up, twisting your throttle gently when you are going slow or stopped. Give the bike a good long run on the open road to give the battery some charge from the alternator.

Make sure your battery is maintained. If you dont use your bike for a while it will lose charge just sitting there doing nothing. Give the battery a good deep cycle charge or take the bike for a good long open road ride.

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1 Answer

I have a 2010 aguila GV250 efi (170km only) and for some reason the plugs become faulty and I lost spark, the bike wouldn't start. I replaced the plugs and now the bike starts but has a mind of its...


I also have a GV250 EFI 2010 model. Make sure you do a full deep cycle recharge of your battery, check water levels etc prior to charging. A standard basic $40 to $70, 12 volt car battery charger shall suffice for your bike battery. Or take the bike for a good run for a few hours on the open road the get some charge in the battery. A very common problem for this kind of motorcycle whereby being a fuel injected model it requires a minimum amount of power to run the computer that controls fuel mix etc. When slowing down dropping down to second and into first to stop at traffic lights etc the bike will often stall if the battery is flat and the bike is at low revs. You can compensate by adjusting the throttle slightly to keep the revs up, causing the alternater to produce more power to keep the computer at a minimum voltage input. If the battery is very low on charge at low revs it will either stall or continuosly rev ridiculously high and low to try and produce anough power to run the ECU. This is a very common problem for this bike.
Very prominant if running add on fog lights as well, like I do.
Easy to fix, make sure battery is fully charged before you use. A lot of people buy a small trickle charge battery charger to put on their bike to keep battery maintianed when sitting in the garage. I only use my bike in good weather and usually only on weekends. Embarrased the hell out me first time my bike reved up and down, as it was in heavy peak hour traffic. I got some funny looks.

Keep the battery maintained and you should be OK.

Hope this helps.

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1 Answer

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