Intake manifold torque specs - no power

Hello everyone!

After I redid the top end, going through the break-in period and starting to give more throttle, I noticed the bike started lacking power. I adjusted the valves (the intake valve had closed completely) and the bike ran exceptionaly well for about a 45 minute ride. I was maintaining 95kph going up decent hills without even having to shift down, and that made me so pumped ( I wrote about it on here somewhere). Afterward, the lack of power came back and after adjusting the valves again, it does not seem to be the problem anymore.
My problem is a big lack of power, especially showing in gears 4 through 6 at higher RPMs. I can't even get the bike to go faster than 80 kph on flat ground. I'v been riding it nice and easy this way for a couple weeks now, but it bugs me and I have to fix it.

After some research, I have decided to replace the intake manifold (carb boot) which is the part that is between the carburator and the engine. I have a maintenance manual and through all the torque specs mentionned in that section, there is nothing about the torque specs for the bolts that hold the manifold on the engine. When I removed it tonight, the o-ring seemed pretty flattened out and thin, so I'm hoping that maybe the problem is an easy fix and I simply over-torqued the bolts when I installed it after the rebuild.

Does anyone know how tight those bolts should be?

And if this not the problem either, does anyone have any other ideas? Here is what I have checked so far without seeing any problems:
- Carb is clean
- Crank vent hose is clean
- Air cleaner is in good working order
- Tried a new spark plug, no change
- Plenty of gas flow (check by unplugging gas line and draining into jerry can) I figured if the screen in the tank or the cap vent was plugged, fuel flow would be slow coming out the petcock....but it's not.

Best of all, after riding it as is for about 2 weeks, yesterday there started to be a rattle in the exhaust, near the tail pipe. I'm not sure if a previous owner did the Z-1 mod or not any maybe he left a piece of metal in there and it finally broke loose?

Hi Rocky:

My Haynes manual lists the torque at 8.7 ft/lbs and the hose-clamp at 1.4 ft/lbs. I'm not sure if this is the fix from your description. You don't mention, for example, how the bike is starting and running or if it's burning oil, miss-firing or cutting out?

If it is I would check the compression as well as the carb.

If a bike is starting and running good otherwise, a change in performance might be due to temperature, humidity, how it's loaded and especially the wind and tire-pressure. Check for drag on the chain, and check the brakes adjustments too. It's a 14 hp motorcycle.

Find a gentle long upgrade on a good road and approach with a set speed and note the performance and where you have to shift. Even a slight breeze or a few lbs low on a tire makes a huge difference. After establishing a baseline it's easier to note the effects of changes to the bike.

You can shine a flashlight into the muffler and see if the baffle is still intact.

just thoughts...

patuca

I doubt you could damage the o-ring by over-torquing the bolts. You'd have to crush the intake housing, but the threads would likely strip out before that would happen. If you removed and re-installed the intake, I'd guess that it wouldn't re-seal very well. The over-molded rubber is known to crack with age and be a source of vacuum leaks. Be sure the surface on the cylinder is clean and smooth when you install the new part.

The tail pipe is easy to remove, unbolt at the muffler and unclamp from the header pipe. Removing the spark arrestor can be less easy. There's a single screw that goes up from the bottom which can be a pain to remove. Once that screw is out, the assembly just pulls free from the muffler.

Thanks Peejman and Patuca for your advice once again!

I put the bike back together tonight with the new intake manifold. While I was at it, I took the carburator apart and cleaned it out once more. I believe the issue was actually a dirty throttle body because reddish brown liquid was coming out one side when I was spraying carb cleaner in the other.

Now I'm slightly baffled as to how that dirt (probably rust from the tank) got in there. I gave the inside of the tank a thorough cleaning in May and installed a in-line fuel filter as a precaution, knowing it might get rusty again. Should rusty gas be able to pass through a in-line fuel filter?

Anyways, the point of the story is the bike is running like new again! I was able to maintain speed going up long shallow hills on the local highway (95kph). Also, if i give it too much gas in 1st gear with my ass toward the back of the seat, the front end comes right up!! It wasn't doing that before that's for sure hahaha.

Yes, that's likely rust from the gas tank. Yes, it will pass through the screen type fuel filter and gum up the carb again, so it has to be addressed. There's a few options for trying to fix the stock tank, or you can get a Clark tank.

I was thinking about a Clarke tank in the future but they are a little pricey and I'm not so rich at the moment. What options do you refer to with regards to the stock tank?

Before the summer I knew there was old gas in there and noticeable rust build-up from the previous owner. I drained the tank, removed it and cleaned it out using the old school method of spraing most of a can of WD40 in there with a handful of nuts and shaking it until my neihbors complained (about 30 minutes lol). After doing this, I intalled a generic transparent in-line fuel filter, thinking it would take care of the rest of the problem for me. I figured the filter would catch everything thats left or new and when I would notice it was dirty, I could just swap it out for a new one (they're only 5$).

It seems as though you might have some better ideas. I would love to hear them when you get a chance. THanks!

Repeat what you did with the WD-40, only use some diluted muriatic acid instead, a hardware store should have it. After the acid, rinse it a couple times with a baking soda solution to neutralize the acid. Then rinse it with a heavy 2-stroke gas mix. Then only use 100% gas in it.

Else there's products like Kreme and Por-15 to seal the tank. I tried Kreme on my old CBR and it ruined the tank and caused me to rebuild the carbs yet again and buy a salvage yard tank. Others had better luck. I think someone here used Por-15 or something similar with good results....

http://www.xt225.com/forums/ubbthreads.php?ubb=showflat&Number=127512

http://www.xt225.com/forums/ubbthreads.php?ubb=showflat&Number=140347