Can't start the engine Evo 96



I am looking for some help. I am bulding my custome bike based on the EVO 96 engine.....the igniiton is brend new (Crane) and the carb is Mikuni - second hand but was attached to the engine i bought, so i assume it is okay.

Today i wanted to start the engine finally for the first time....but.....
1. Battery is new
2. The spark is on plugs (tested by taking it out, and crancking the engine)
3. The igniton seem to be okay as well - light goes off at TDC, and the light blinks when I cranck the engine.
4. Not sure if i get the enough fuel to the clilinder - if any....Sometime the front sparkplug is all wet ( only the front one for some reason ) the the rear one is all the time dry?????
5. On a couple of ocassions I go the backfire from the carb - and that was the only sound i got!!!!!

Please advice how can i start this engine!!!!!!!!!!Am i doing something wrong?


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The Mikuni may be loading up the plugs if you are choking it more so than a CV carb will. Try a new set of plugs and try starting it again. From what you say the front plug is wet, but is it gas? You may have some water in the tank and it is passing through the carb. I would put in a new set of plugs and get some starting either and give it a toot in the carb. Do it outside in case it flashes back out the carb. It should start without loading up the plugs if everything else is OK.

If you have intermittent spark, remove the cam cover plate where the ignition is. They have a habit of grounding out on the cover sometimes.
Hi Glider,

Thanks a lot for your response.
I have brand new sparks but it still does not start...

1. Could you please explain what do you mean by giving a toot in the carb? Do you mean to clean?
2. How can I check if the carb is okay?
3. This time the sparkplugs are dry, not wet any more even after o20 sec. of cranking!!!!! But this makes me think that the cylinders do not get the gas. Should they be wet?

4. Also, how can I check if I have sufficient compression? When I put my hand close to the plug hole and crank the air comes out.....but is this enough to know if the compression is okay......The engine was rebuilt least that is what i was said... do you think something can be wrong with the cam ?

5. Also, when i removed the filler from the carb, and when i crank the air goes in and out from the carb, is it normal? Once in , once out?

I know that it is all guessing, but any tips and help welcome and much appreciated - I get to that stage with building this bike for over a year on my own that it would be a shame to bring it now to the garage and ask to fix the problem. I am a stubborn person; I really want to start it on my own. Okay, with a little, please advice if you can.

Thanks again

Hi Glider,

I forgot to mention earlier but I got the backfire twice or three times from the carb....I have the filter taken off. Any suggestiones.

Thanks again

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By the toot I meant a squirt of the starting fluid (either) in the carb to see if it pops off (starts) thus eliminating an ignition problem.

It gets a bit complicated to check if the different circuits in the carb are working to someone that isn't a mechanic. You can see if you get a squirt out of the accelerator pump when you open the throttle and look into the throat of the carb with the engine off.

The plugs may be dry because you are not getting gas. If you are using the enricher, they would probably be wet. That's why I suggested a toot of either (starting fluid) to see if it started and stalled again without wetting the plugs. This would tell you that you had ignition and the problem is probably in the carb.

To check compression, you need a compression gauge. If you have one, then unscrew the plugs, open the throttle all the way and hold up the slide in the carb and crank the engine after you ground the plug wire ends to the engine to avoid damage to the ECM. You should turn it over about 4 revolutions till you get the highest reading. A good starting point would be at least 160 lbs. or higher for a good running engine.

With the air going in and out of the carb like you say, it is somewhat normal but if it is in larger quantities, you may have a bad intake valve or it may be hanging up.Lets hope that it isn't hanging up because the piston could hit it and bend it if this were the case. A compression test will tell you there.

The backfiring from the carb could also indicate a problem with the intake valve(s) Again, a compression test will tell a story here.
HI Glider,

Really Big Thanks for your reply.

I did open the throttle a couple of times and pumped some squirts of gas into the intake - and it was actually then when I got the backfire when i inteded to start the engine. I think there was plenty of gas in the intake but not in the cylinder. Is this what you mean by the toot......I am sorry by English is not my first language and when it come to technical vocabulary I do struggel sometimes :)
Do you think I should squirt some gas straight into the cylinder through the plug hole? How much? (I can use a siringe).
And what is a starting fluid? Is it a kind of special gas that I could buy in the HD dealer?

I will invest in the compression gauge and check what reading I get....
I think the valve is not hanging as I had a look on the valves through the plug hole when I was setting up the TDC to set up the ignition, and the valves seemed okay - closing and opening. Obviously i can really tell if they close properly but I will do the compression check to see what happens there...

There is also one thing I did not metion prevoiusly but it might be crucial. I bought the engine over a year ago without oil inside, so I thought it was a good idea to pour some oil to the cylinder to prevent the corrosion of the cylinder and pistons- not sure if it was a good idea but the weather in the UK is quite humid and I knew that the engine will not be started within the months.It was not much oil anyway, and I belive that after two days of cranking all the oil has been blown out. But this may be the source of the problem. What do you think?

ps. I am really happy I signed up for this forum, I should have doen it long ago...and I really appriciate your advice. It is really greatand helpful to know that you can ask a question that is eating your brain, and somebody on the other side of the net may help you.....It is really fantastic, I hope one day I will be in a position to give some advice on HD.

Thanks a lot.

First things first here, check that the engine has oil.

1 do a compression test.

2 See if you have spark

3 Fresh gas in the tank?

4 When you try to start it , give the intake a spray of starting fluid (either) and see if it starts.

Let me know what happens.
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Hi Glider,

I did the compression test and it looks like there is NO compresion at all?????? unless the gauge is broken......but it is brand new so it must be the compresion....
The engine was supposed to be rebuilt when I bought it but it looks like the guy who was putting it all together did not do the right joob!!!!!!!!

Please advice where i should start? I belive from checking the the cam if it is set up properly but then????
I must tell you that i have some mechanic experience as i already exchanged the head gasket in my car and i did 15.000 miles since...
Please give me some advice what to start with as i really want to do it myslef.

Thanks a lot


What you have to do is to verify if the motor has compression for sure and go from there, seems unlikely that there is NO compression. Has this motor EVER run that you know of? You could press a thumb over the plug hole and crank the engine to see if it would blow your finger away from the hole or not. It'll give you some indication if there is compression or not. Ground the plug wires before doing this.

See if it is a bad compression gauge or not first. From there you have to get into the cam area to see if the cams are timed correctly, check the rocker arms to see if they are operating when you crank the motor. If the cams are timed incorrectly, there's a chance that some damage has happened to the valves and the motor would have to come apart then.

If there were to be no compression, the motor would spin over quite fast and would sound smooth as opposed to the sound of the starter trying to overcome compression on the compression stroke (s).

If you don't have a manual that would cover this proceedure , It is difficult to explain to you how to do it on the internet. I would suggest finding someone local that could help you out.
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Hi Glider,

Thanks for the reply. I will not be able to start doing anything on the bike until next weekend as I am traveling at the momemnt - Spain :). Will let you know in 10 days.