Strange tach By bobf (Read 764 times)

[bobf]

MC 54 250 with 244cc vertical engine.

My tach doesn't seem to trac the bike engine RPM very well at all.

It seems to trac at or below 2,000. But at 2,000 it then starts to dip as the engine accelerates. It seems to my ears that the engine is turning quite fast and then the tac starts climbing up. To me it seems to be near screaming and the tach is at 3,000. When let to idle it follows all the way down to about 1700 or 1800 where I expect it to be. I just don't understand the stalling and dropping at about 2000 and maybe not climbing again till the engine is really revving up.

To me it is a mystery tach but I don't use it when riding, just when I wish to idle the engine.

OK, any reasons for this weird action?
.

[JR]

I had the same problem wit the tach on one of my scooters Bob and all indicated that it had moisture in it. I let it sit out in the hot sun for a couple of days and all was well. I hope your scooter isn't screaming and if all is right it should do 60MPH at around 6200 RPM.

JR

[bobf]

Well Jr, my scoot has been sitting in the garage at temps as high as 110+ for a couple months now. Besides my kindney stones and eye surgeries I find summer in Arizona to be a bit to hot to ride. Today we were just in the nineties for part of the day so I was in the garage tinkering with the scoot. That was when I decided to post this note. It did that when I first bought the scoot a year plus ago. It was cold then, barely over freezing in Colorado winter. I guess if it is just for the idle setting I probably don't care about the way it acts. When riding I can barely see the instruments so I judge by how fast the fireplugs go past. If I can go with the flow of traffic I don't really care if it is 30 or 50. Not in any hurry to set speed records.

This afternoon I started to do the front tear down as I need to figure out how those head lights should be mounted. The right light is solid but the left light is loose and can swing around. Been that way since I bought. Hope to be able to squeeze in this job on not so hot days so I am ready when the temps come down a bit. A couple weeks back I saw 117 for a short while. Today it has risen to 113 in the garage. Plus we are now in the monsoon season and have high humidity, which is rare in Arizona.

Thanks for your comment.
.

[JR]

Man and I thought it was hot in Arkieland! We're now very humid too not common in this part of the Arkansas mountains but the Issac hurricane has turned and they now have New orleans on alert so if it hits there we will get some rain I'm figuring too.

Since you're going to pull the front off why don't you open up the tach area and see what you find? If you can find out what's wrong and fix it then that can help others down the road.

JR

[bobf]

Well Jr, I have the front panel, the windscreen, and the top of the instrument are off. I checked connections on the cables and they seemed tight. But I did not do a pin check on the wires. Still one big panel to remove. I think it must be removed and that is the wrap around panel on the front. Will look at that tomorrow if it is cool enough. If that comes off I will be able to work on the lights and also check better on the cables. It looks like a bunch of wires enter at the tac area. First must worry about the left headlight. I would like to set the headlight aim if I can get it properly attached. Just in case some day I may have to ride at night.
.

[bobf]

OK, I did finally get the front panel off. Took the left headlight assembly out. Took it apart and found two of the three sliding mounts for adjustment were connected and the third was just floating. The slot the adjusting nut slides in was bent so I straightened that out and worked the three into position. Now I should be able to adjust the headlights.

Now for the worst problem I have had with this operation. I need to get two screws into each side of the lower inside front panel to the plastic grill in front of the gas tank area. The front panels and the grill have both got their own idea of straight. I am on my knees trying to hold them together and putting a screw into a slot I can barely see and not knowing if the screw and tinnerman nut are aligned. I think I need two more hands but there is barely enough room behind the front wheel as it is. I tried a vise grip but could not get that to work well either. I aligning and clamping are two skill I must not have.

I was able to secure the left side, drivers view, and am now stuck on the right side. I think I spent about an hour to get those two screws in on the left side and have spent that much time on the right side but not one screw installed yet.

Any ideas from you more experienced panel removing and reinstalling folks?

Thinking back a lot of years and I think Cushman had the best idea. Not sleek and sexy but plenty of functional. Their covers were held on by a few buckle clamps. sure wish I had something functional right now. No wonder shop service is so expensive with these scooters.

It is now just past noon and 102 and climbing so I may just wait till tomorrow morning and try again in a cool 90 morning temp.
.

[jct842]

In my opinion the worst trait of the chinese scooters is the service ability. They copy the japs and since they lack some in quality they need more service and the crap plastic is always in the way. I want to see a retro scooter based on a design such as the mitsubishi silver pigeon or even a cushman. To get to the engine all you did was release one catch and you could lift the tub/seat and the whole engine was exposed. A fan cooled engine and cvt sitting there completely exposed.

After a few years of exposure to the sun that crap plastic does start to decompose and we are going to have a ton of trouble with all that plastic crumbling. I have seen some of it already.

[bobf]

Today I finally finished getting those last two screws into the front panel behind the wheel. Three days of working on it for an hour or two each day with no success. Was talking with the wife about it and made a comment about the factory. I said I bet they use some form of tooling to hold everything in place till they get the screws inserted. That got me to thinking.

So I went back to the garage at over 100 temp. Took a long and slim Phillips screwdriver and pushed it through the plastic and also the part with the tinnerman nut on it. Then took a needle nose vise grip over both to hold them together. Pulled the Phillips screwdriver and everything stayed in place. Inserted a screw and tightened it up. Then for the lower one I was able to insert the screwdriver through the holes. No place for the clamp so with one hand held panel in place, pulled the screwdriver, got a screw inserted, then with a larger screwdriver I was able to push down on the screw and get a few turns going before letting pressure off. It took a few turns and tightened up. Success at last. Primitive tooling but it did help a lot. Now tomorrow I hope to end the panel installation and get a look at wiring and such while it is open. Also want to do a headlight adjustment before I put the top panel and the windshield and cover back on. I hope for a drop in temperatures in another week or two so that I can start riding again. At least in the mornings.
.