Bogging engine

[Jonny42]

Hi there, I know there are lots of questions already asked similar to this one, and i have tried all of these looking for solutions. None seem to be working
I have had my motorized bike for about a year now, and its only started having troubles lately. it starts going, but when i give it throttle, it wont acutally start going properly, the moment i put the cltuch in, it turns off.
i have done correct fuel mixture, checked carb for any blockages and it all seems fine. there is a spark and compression seems fine?
cheers

 

[allen standley]

Jonny, do you have access to a compression gauge? 90LBS min is what you want.

 

[Jonny42]

no i dont. but the bolts are pretty tight enough, i dont think there would be any leaks.

 

[allen standley]

The concern is not so much leaking from the Head but Leaking past the rings. So it's been running well in the past year?
Read this story and look at the pics.
https://motorbicycling.com/threads/story-of-two-boys-a-world-away.65469/

 

[Jimmy Bloodmaker]

check the in tank fuel filter. could be blocking up.
could be rings like allen said.
when i had a bike do tht. the freaking magneto gave out when i was 8 miles from home. i've since switched to using BBR's super magneto. haven't had a single super magneto conk out on me yet ( knock on wood).

 

[Jonny42]

f

check the in tank fuel filter. could be blocking up.
could be rings like allen said.
when i had a bike do tht. the freaking magneto gave out when i was 8 miles from home. i've since switched to using BBR's super magneto. haven't had a single super magneto conk out on me yet ( knock on wood).

fuel filter is fine, no blocking up at all, fuel is getting through

 

[allen standley]

Jonny42, More info would help. Have you pulled the plug held it to the block and checked spark? If you got spark - You NEED to have the compression checked. Then go from there. 3 things are needed to run-
1. Fuel / air mix
2. Spark
3. Compression
All equally important!
https://www.amazon.com/Engine-Compr...6411&s=gateway&sourceid=Mozilla-search&sr=8-9
If you cannot find someone to check compression for you (local garage), go ahead and pull the Head to inspect the cylinder.

 

[Jonny42]

Jonny42, You NEED to have the compression checked. Then go from there. 3 things are needed to run-
1. Fuel / air mix
2. Spark
3. Compression
All equally important!
https://www.amazon.com/Engine-Compr...6411&s=gateway&sourceid=Mozilla-search&sr=8-9
If you cannot find someone to check compression for you (local garage), go ahead and pull the Head to inspect the cylinder.

hi there, i have already pull the head cylinder apart. Is there anything in particualr i need to look for?
as for the above three, their is spark, there is fuel and air, so it must be compression. I just dont really know what to look for
cheers

 

[allen standley]

I have had my motorized bike for about a year now, and its only started having troubles lately.
Could be a speck of dirt in carb needle valve?
Could be a failing Mag Coil? (under left side front cover)
CDI Black box could be failing? (this is not likely but they do fail)
Defective/ Broken spark plug boot?
If I were where you are I'ld trouble shoot with you. You Gotta do it yourself.
Fuel, Spark, Compression. Gotta have it all.

 

[Jonny42]

yep, i have blown out the carb needle
and it could be a failing mag coil, there is magnetic force on the magneto, could be the coil, but people have told me not to just start buying this as there could be other problems
i have tested for spark, there is spark,
the gasket though when i took of the cylinder housing (the one under it all) is quite weatehred, this may be the problem. What do you reckon?
cheers

 

[allen standley]

If the cylinder looks good (No Flaking Chrome) as long as the gasket is whole and not ripped it should be good but otherwise- I would suggest replacing that base gasket. Also under that spinning magnet there is a keyed shaft. be certain that key is not sheared. If you must pull it off the,shaft mark the side facing you with a black perm. Marker before removal so as not to replace it wrong side out. They only work with the correct side facing out, otherwise timing will be 180 off and will spark @ BDC instead of TDC which would be correct.

 

[allen standley]

Also while you are in there mucking about, There is a rubber seal behind the magnet. Check for oil seeping in past the seal. Also---Pull the clutch cover to see if you have oil accumulated at the bottom in there. There is a rubber seal behind the small bevel gear which if fails will cause a loss of compression in the base. If you got oil in either place, you got a bad seal to replace. They are not the same.

 

[Jonny42]

how should the mangeto look? my bolt came undone and i took it apart. how should it be put back together?

 

[allen standley]

how should the mangeto look? my bolt came undone and i took it apart. how should it be put back together?

The spinning magnet is several plys long riveted together. Is this what you are talking about?
Or the horseshoe shaped with the wound coil?
http://thatsdax.com/ENGINE_KIT_PARTS_PAGE_3.html

 

[Jonny42]

the spinning magnet. My bolt somehow had came undone and was sraping against the cover. i have put it back on just wondering any tips on how to do this properly.
i have watched some clips now and i kinda know how to to it. 1 oclock position im pretty sure

 

[Jimmy Bloodmaker]

the spinning magnet. My bolt somehow had came undone and was sraping against the cover. i have put it back on just wondering any tips on how to do this properly.
i have watched some clips now and i kinda know how to to it. 1 oclock position im pretty sure

it has a keyway. if it dont work one way, flip it 180. if it still don't work, ohm check ya magneto, or do a spark check, ohm checking it ( find the reading in the forums somewhere, shouldn't be hard, i don't know it off hand, lol) will give you an idea of whats going on in the coil.

 

[Jonny42]

yep. its all good. took the head of and saw the gasket was no more. have oredered new one. I think that will fix the compresion problem.
Thanks for everyones help
cheers

 

[Jimmy Bloodmaker]

yep. its all good. took the head of and saw the gasket was no more. have oredered new one. I think that will fix the compresion problem.
Thanks for everyones help
cheers

running lean from the blown gasket. check everything over twice. make sure it's looking good before you put it back together. hate to have it blow the rings out after all the works done. glad ya figured it out. motor on!!

 

[Jonny42]

ok. so I put all the gaskets on, and it still has the same problem?
any ideas?

 

[allen standley]

So after all this...
hi there, i have already pull the head cylinder apart. Is there anything in particualr i need to look for?
as for the above three, their is spark, there is fuel and air, so it must be compression. I just dont really know what to look for
cheers
Let's go back to the beginning. When you stated above you had your cyl. off. Did it look like this pic?

I don't understand why you have not answered questions I have clearly asked. I put out to to help you. I am not an ego driven know it all. I'm Just trying to help that's all. GET YOUR DARN COMPRESSION CHECKED. The end...