15hp strange loss of power

[Gmcken34]

Will have a helper after lunch, the thing is this engine is in as new condition(everything nice and clean) has anyone come across a CDI unit that fails at mid RPM under load. the engine is 2006 but it only has about 16 hours on it Strange

all connections perfect(clean and tight)

[greasyshaft]

Test your peak voltages before replacing the expensive bits, and as Town says check your earths.
You will have to find the specs, for your exact model
Get An Adapter to Troubleshoot CDI Ignitions | Boating Magazine

[TownsendsFJR1300]

My electrical issue on my MC, the bike was less than 2 years old, always garaged, etc however that connecter still got corroded.

I can't impress enough, to physically go thru each connector, pull the grounds, check for any corrosion, etc. Your engine is super clean however its still 8 years old, aluminum corrodes, etc.

Just looking at a ground bolted to the block don't cut it.

On another Yamaha motorcycle forum, in Europe, there were several cases of just the salt from the roadway working its way into a certain connector causing "cross talk" between the sensors, screwing up the operation of the bike. Cleaning that connector, di-lectric grease, fixed the issue

You can spend a small fortune on a CDI (maybe you do need it) however the above potential issues are MUCH more likely..

Someone else will need to chime in re the CDI (testing, etc).

I have no idea how to test it. I would think the internals are sealed and less likely to be an issue vs everything else exposed.

[99yam40]

Will have a helper after lunch, the thing is this engine is in as new condition(everything nice and clean) has anyone come across a CDI unit that fails at mid RPM under load. the engine is 2006 but it only has about 16 hours on it Strange

all connections perfect(clean and tight)

Not too sure about your 15 but some/most of the newer 2 strokes had the timing con*****ed by the CDI.
Monitoring the timing will tell you if it is in spec and advancing as it should.
A simple test and you have the timing light.
No power can be a result of improper timing, not enough fuel, or too much fuel. Proper air to fuel mix is very important.
Should be only one charge coil that creates the voltage for spark feeding CDI.
CDI just stores that voltage and then pulser coil tells it when to send to ignition coil to fire the plug. You need to get the proper test equipment and service manual to check ignition system if you truly believe you have low or weak spark.

A lot of the 2 cylinder motors used waist spark, where it fired both plugs each time once on exhaust and on on power stroke, but if your motor has 2 separate coils then that would not be the case with your motor

If that motor set up that long could be internal parts rusted and things are not sealing well

[grf00]

Know you think it's electrical but as few hours, unless it's corrosion or some kind of manufactures issue, I still think fuel from setting. Yamaha make good stuff. I could not find the 2006 FHM and just using the 15 MSH fish on the carb, did you pull the needle jet out that is behind the main jet after you pulled the main jet? Does appear that the advance is mechanical with a link up to the pickup under the flywheel. Be sure to at least set the timing mark on the face of the flywheel at the proper degree and throttle up to you just see carb pick up hit and make sure the mark up on the link aligns with the proper place on the mark on the OD of the flywheel. There is a procedure for this. Mine has the WOT advance of 25 degrees. Full retard of 5 degrees (at idle with the idle screw maintaining it) and the pickup of the carb of 0 degrees. That pickup one is hard for a garage mechanic to get since when the roller first touches, it does not start moving the carbs . The carb movement is on mine when the 0 degree comes in. You do not want too much advance on these small motors.

[TownsendsFJR1300]

Know you think it's electrical but as few hours, unless it's corrosion or some kind of manufactures issue, I still think fuel from setting. Yamaha make good stuff. I could not find the 2006 FHM and just using the 15 MSH fish on the carb, did you pull the needle jet out that is behind the main jet after you pulled the main jet? Does appear that the advance is mechanical with a link up to the pickup under the flywheel. Be sure to at least set the timing mark on the face of the flywheel at the proper degree and throttle up to you just see carb pick up hit and make sure the mark up on the link aligns with the proper place on the mark on the OD of the flywheel. There is a procedure for this. Mine has the WOT advance of 25 degrees. Full retard of 5 degrees (at idle with the idle screw maintaining it) and the pickup of the carb of 0 degrees. That pickup one is hard for a garage mechanic to get since when the roller first touches, it does not start moving the carbs . The carb movement is on mine when the 0 degree comes in. You do not want too much advance on these small motors.

I asked earlier, he's in Ireland. Thats why we (I tried looking it up too) can't find it on the US, Yamaha parts fisch.

I do agree, the fuel system is much more likely to be an issue than the ignition, especially after sitting and very little use BUT if he's NOT getting full spark thats another issue.

I have doubt timing would be the issue, nothing was adjusted there since it was last run. Ignition, same, nothing usually goes foul from sitting. Carbs, fuel pumps, different story, jets clog, diaphrams dry out, fuel pumps leak.

Sooner or later we'll find out...

[99yam40]

I asked earlier, he's in Ireland. Thats why we (I tried looking it up too) can't find it on the US, Yamaha parts fisch.

I do agree, the fuel system is much more likely to be an issue than the ignition, especially after sitting and very little use BUT if he's NOT getting full spark thats another issue.

I have doubt timing would be the issue, nothing was adjusted there since it was last run. Ignition, same, nothing usually goes foul from sitting. Carbs, fuel pumps, different story, jets clog, diaphrams dry out, fuel pumps leak.

Sooner or later we'll find out...

On my C40 the idle timing was too far retarded but WOT timing as in spec, ended up changing the CDI to fix it. It would have been nice if Yamaha did not put the TPS in the CDI on my model.

Maybe a problem with electronics, not that someone moved anything.
Always test compression, spark , and timing. then move to the fuel side.

Too easy to test not to.

[grf00]

So his motor has a Throttle Position sensor and all the advance is totally electronics now? So like my car and Harley, no adjustments on it?

[Gmcken34]

OK so I spent the day messing with the engine, timing light connect, carb redone.

Still having the same issue thinking about it, its like the timing is off at half power

timing light seems the same for both cylinders
getting fuel and had a look at the valves and the are fine.

sync is non adjustable

In bad need of help now, I'm LOST this engine has me stumped

[99yam40]

so is timing advancing as it should to specs listed in service manual?

[TownsendsFJR1300]

On my C40 the idle timing was too far retarded but WOT timing as in spec, ended up changing the CDI to fix it. It would have been nice if Yamaha did not put the TPS in the CDI on my model.

Maybe a problem with electronics, not that someone moved anything.
Always test compression, spark , and timing. then move to the fuel side.

Too easy to test not to.

Interesting.

I don't know how they could put the TPS, a unit that literally measures the movement of a throttle shaft, thru the CDI... Maybe another sensor relaying the info, definitly FUBAR.


Re the op, I don't have any other idea's.

99yam40 is more familiar with it, someone else is going to have to chime in.

99Yam40, do you know or anyone else (or the Op looking at the shop manual), is there a way to test the CDI?

[TownsendsFJR1300]

So his motor has a Throttle Position sensor and all the advance is totally electronics now? So like my car and Harley, no adjustments on it?

Being his engine is apparently a European model, (Ireland) theres NO access to a parts fisch for that engine here in the states.

Every 15 HP for 2006 I looked up, was a single carb and no typical TPS showing.

I have to suspect there is no TPS to speak of. Timing, etc is likely adjusted electronically thru the ECU taking signals from engine RPM, or thru physical linkages, like the older Evinrudes/Johnsons.. On those engines, advancing the timing kicked in first (linkages), raising RPMs way before the carb butterfly ever started to open..

[grf00]

I was thinking typical TPS would be on OD of flywheel reading TDC. Would feed TDC and rpm to ECM. ECM would adjust timing across RPM band. Pretty easy and sure lot cheaper then my mechanical setup.

[99yam40]

All I was saying is the 1999 C40 I have, has linkage to the CDI from throttle/carbs that moves a wiper(resister I am sure) that gives the internals of CDI the position of the throttle so it knows what is going on and when to advance the timing.
I kind of doubt they still use mechanical linkage to move the plates under flywheel like years gone by to advance timing on these newer motors.

But have no idea about his motor.

Just a very good idea to use timing light to see what timing is doing, however it is adjusted, just to eliminate one of the things that can cause loss of power

[TownsendsFJR1300]

I was thinking typical TPS would be on OD of flywheel reading TDC. Would feed TDC and rpm to ECM. ECM would adjust timing across RPM band. Pretty easy and sure lot cheaper then my mechanical setup.

Not to insult anyone or...

But the TPS, throttle position sensor is a physical sensor that hooks to the end of the actual carb main butterfly shaft or the FI throttle body main shaft. Same as on a newer car, most motorcycle's, etc.

All it does it converts the actual position of that shaft to an electrical "signal" that the computer can read read and adjust the engines componants accordingly. I know Yamaha has been using it since at least 2003 on their motorcycles, so its been around awhile. Its also had several re-calls on it in the MC world...My old bike included..

Its got nothing to do with the flywheel, simply the butterfly shaft or TB shaft. Its generally set by voltage and can be adjusted to some degree.