Hi Guys,

I have a 94 with about 55k kilometers on it. I've only owned it for about 6 or 7 months. The cam chain is badly stretched. I've finally found a good mechanic that has the bike running as well as possible with the cam chain in it's condition. He says it will last about 1 more year if I don't hammer on it. I know I'm missing a lot of power.

He wants to replace the cam chain, tensioner, gaskets, all the internal bearings at the same time.

I live in Costa Rica so I will have to have all the parts shipped in and get nailed on import taxes. So if I'm going to pay for all that, plus labor on top it it (although that is cheap here), I'm thinking of doing a full rebuild. Replace the rods, the pistons, the rings also. I'm thinking of putting in some over sized pistons.

I found this on ebay: http://cgi.ebay.com/ebaymotors/HONDA...7209QQtcZphoto

What are your thoughts? Is it worth it?

 

If its only got 55k on the clock then leave the rebuild until WELLLL after 150K

Just do the Cam Chain & Tensioner.

 

I agree with trips. Also, that piston kit is oversized, that means machining cost to bore out the jugs. $440.50 (10.50 shipping) plus machining is a lot to think about.

I don't understand when people in this forum talk about the cam chain being stretched. There is little stress on it. All it does is pull the cams around at any RPM. I don't think you could rev the engine to put any kink of unusual stress on it. Maybe your mechanic is not familiar with the cam chain tensioner troubles the bike is prone to. I replaced my tensioner it is quiet. If anyone has any thing to add to change my opinion please straighten me out. I just can't see the load on a cam chain that would make it crap out at 55k kilometers. Has anyone pulled one and checked its length?

 

The difference between a stretched one and a normal one is very hard to tell.

Only way the Cam Chain could be buggered after 55k was if was flogged to death.

I flogged the living crap out of my bike with a lot of load and the Cam Chain still lasted 85k

But since you are changing the tensioner might as well do the chain at the same time.

 

My mechanic says I could get another year out of the current cam chain, if I don't try to drag race with it LOL

Right now it runs pretty badly in my opinion. From 1,000 - 2,000 rpm, there is nearly no power. It starts to feel decent at 3,000 rpm. Because of this, trying to drive in slow moving traffic is real pain. It surges and makes me look like a newbie.

I just want it to run like it should and make decent power.

 

Thats got nothing to do with the cam chain.

 

I'd replace the cam chain tensioner only to start. Chances are very good that the chain is okay. If it turns out you need a new chain get a split cam chain. Then grind a pin out of your old chain, use the master link to hook the new chain to the old one and thread it through. Be sure you stake the master link in - some guys say you should tack it in with a welder. And some say you should never use a split cam chain.

The engine should be good for up to 100,000 miles if cared for properly, and I've heard of them going further. It's always possible your engine needs work at low miles if the previous owner beat the crap out of it and did no maintainence. Did your mechanic do compression and leak down tests on your bike? Check the valve clearances? If the answer is no I'd be reluctant to do a rebuild until those tests were done and inexpensive (relatively), easy cures were tried. If he has done the compression test / leakdown tests and found poor or inconsistant compression or you're burning oil and you know the valves are in good shape, then probably a teardown and rebuild is necessary.

As for power from 1,000 to 2,000 rpm, there isn't any. Well, there's enough to take off, but there's no usable power below about 3,000 rpm, and the engine doesn't really come on until 6,000 rpm or so. If you're getting surging you should do a tune up - plugs, check the plug wires, make sure valve clearances are okay, then synchronize the carbs. If that doesn't take care of it you probably need to go through the carbs clean them out and then re-synch them. Incidentaly, in traffic I try to use a gear that lets me run at 2,000 rpm or better even though my bike is tuned and running well, although slow traffic has me in first gear idling along at times.

Edit: by the way, out-of-sych carbs can cause the engine to make the strangest sounds and run very strangely. With that in mind my first step would be a thorogh tune-up and carb synchronization.

 

I bought the bike used from a bike shop, so I really don't know how well, or not, it was treated in the past. As far as I can tell she is not burning any oil. I just had a tune up done. The plugs were fine, as were the plug wires. The carbs were cleaned and synch'd. Before the tune up I had to use full choke and it would take on average 5 tries to start with some throttle (I live in a warm climate). After the tune up, with out any choke, the bike fires up with just the slightest touch of the starter and no throttle.

I have not done a compression test on the bike, nor checked the valve clearances. I guess I should have those checked before dumping a bunch of money into this.

 

If you had a complete tune up no doubt the valves were adjusted. You should have a compression test done though before investing in a complete rebuild. Talk to your mechanic and find out why he wants to replace the bearings. He may feel that disassembling the engine will in some way damage the bearings, and that is a possibility. Gaskets and seals do need to be replaced when the engine is opened up. When I worked the valves over on my '91 CBR with 33,000 miles (approx. 55,000 km) on it the factory honing marks were still visible the entire length of each cylinder and once the valves were taken care of compression ran about 165 pounds, and the engine burns next to no oil. Most likely yours is in the same condition. If compression is within specs, and you aren't burning oil, replacing the rods, pistons and rings is a waste of money.

As mentioned in my original post you can avoid the entire teardown scenario by installing a split cam chain. That's a decision you and your mechanic need to make though. Many people just don't feel secure having a chain connected by a master link working inside the engine.

I'd still recommend just replacing the cam chain tensioner as a first step and seeing what the results are. It's quite possible that is all that is needed.

The surging you mention is most likely not what most would consider surging, which is increase and decrease in engine rpm generally caused by poor carburetion or ignition problems. You are probably feeling the engine lugging because you're in too high a gear for the speed you are traveling. Use a gear that lets the engine spin 1500 rpm or higher if you can. Even at that rpm my engine begins to buck in any gear above first unless I'm coasting, so I shift into first and let it rev. Note: a too loose chain will make the jerking motion feel and sound worse. You might check it also.