105 running issue

[KiwiUSA]

Hi all, I just got a 105 and I have been trying to get it to run after 15 years. Oil was almost like tar so I cleaned it all out refilled with SAE 30 Question: It took 1 quart to fill to 3/4 on dip stick, I would have thought it would have taken more since it is supposed to take 3 pints which is 1 1/2 quarts?

I replaced the spark plug and coil, re-gapped the points to .020, replaced seals in the fuel lines and sediment bowl, cleaned carb. When I fire it up it will start with starting fluid but will not run on its on, it did at one stage with throttle wide open and then died. It seem to be a fuel problem but can not see any thing wrong.

The carb is very simple concept and I presume it works by sucking fuel out of the bowl using vacuum? do you need the air filter on to create back pressure?
There is some butter fly shaft wear, up and down and a little side to side.

Here is some pics, I will get an up to date one tomorrow with the new parts on.







Thanks for looking

Edit: Got update pics

[Terry C]

After that many years of non running you should rebuild/ clean the carb. Also clean the tank and line

Is the fuel valve on the tank on? The sediment bowl looks empty. I'm just looking at the pic on a phone so I could be wrong

[J-Mech]

Air filter is not needed to make "back pressure". That is the throttle plate's job.

A 105 takes 3pts which is 1.5qts, yes. Maybe your dipstick cap has moved.... it happens.


A carb kind of "sucks" fuel out of the bowl.... but I'm not sure it's quite like your thinking. You have a fuel issue. There is a passage in the carb that's plugged. More than likely it's in the emulsion tube (it screws in up from the bottom in the center). Could also be in one of the slow speed circuits. You need to take the carb off, disassemble and clean every passage, blowing them out with air and checking them with any kind of spray can with a straw (WD-40, brake cleaner) You can't see air, but you can see liquid coming out a passage. Reassemble and adjust.

When you do get it running, you need to time the engine, not gap the points. Here is the procedure in more simple terms.
http://www.onlycubcadets.net/forum/s...ad.php?t=33461

[KiwiUSA]

Lines are good and I did strip the carb and cleaned it, there was no gunk in it or any thing, some rust around the bottom of the butter fly shaft on the throttle. Float is working ok and holes clear in high speed needle and emulsion tube. I did fiddle with timing but failed in getting my head around the concept that the points gap changed the timing (was used to moving points) I will redo that tomorrow using the test light method (I was just using my eyes,it seemed about an inch off)

[olds45512]

does fuel flow freely with the line off the carb?

[J-Mech]

Originally Posted by KiwiUSA

Lines are good and I did strip the carb and cleaned it, there was no gunk in it or any thing, some rust around the bottom of the butter fly shaft on the throttle. Float is working ok and holes clear in high speed needle and main jet.

So.... is it getting fuel or not?


What do you mean "moving" points? You mean like you rotate a distributor? All points move..... and changing the gap on any point set affects timing.

[KiwiUSA]

The sediment bowl fills up and float bowl is full, fuel flows out of line ok. So there fore I know the carb has fuel but the engine is not getting it.

It's been a while since I played with points and my memory is a little foggy, I thought you moved the points plate as a whole, my fault. I work on late model ATV's that don't have points, every now and then some dirt bikes. But mostly I rebuild ATV engines, all makes and models mainly the more popular ones.

[J-Mech]

Either your engine has no vacuum, or your carb is plugged.

You can't do a compression check, the K series has a compression release. Well..... you can, but it won't make much.

When you crank it with the air filter off, it doesn't spit fuel out of the carb does it?


On a ATV engine with points, yes you move the point base as a whole. It is the same as rotating a distributor for timing. But the fact remains that point gap affects timing, no matter how the points are mounted. On "other" engines, point gap affects dwell also. On these engines, we aren't concerned with dwell.

[KiwiUSA]

Originally Posted by J-Mech

Either your engine has no vacuum, or your carb is plugged.

I will recheck carb tomorrow and you say engine has no vacuum which is based on compression but yet you say can not do a comp check on these engines but the service manual sates a comp of 110 to 120 is good? The engine appears to have good comp and it does run good when it has a little fuel (engine start fluid)

No it does not spit fuel out when cranking.

[J-Mech]

If you disconnect the compression release you can check it. But that's more work than it's worth.

You have a plugged carb most likely.

Don't use either..... please.....