84 XR350R Kickstart lever locked at the top of stroke

[BorgenRS92]

Hi guys,

New to the forum. Hoping I can get some guidance/advice on a problem with my fathers 84 XR350R before I rip it apart to see what the problem is.

A couple years ago my brother jumped on the kickstart (probably while there was still slack) and it locked the kickstarter(and engine) Bike wont roll in gear. The bike ran perfectly fine before that. SO I am guessing before I pull it apart that the problem is with the kickstart shaft assembly and gears/springs/idler gear/broken tooth? To give more detail, the kickstart lever sits in its normal resting position. It can be pushed downwards about 2 inches and then bam thats it, it doesnt go past that point. It's not stuck in one spot. But something is definitely locked up in their.

I HAVE a Honda Shop manual for the bike. Was this a common issue on these bikes? What specifically in the starter assembly would lock the motor up? All advice is appreciated. Probably going to pull the right hand side cover for the motor and inspect. What should I look for and will the starter assembly need to be pulled out of the motor for a full inspection?

Are their any special tools that I will NEED to buy before pulling anything off to inspect? 

Thanks,

Adam

84 XR350R 

Edited July 9, 2019 by BorgenRS92

[nobade]

Yes, he likely broke the ratchet or a tooth on the gear. Not hard to inspect, drain the oil and pull the side cover off. Everything is right there, just pay attention to how it goes together before you pull parts off.

[BorgenRS92]

UPDATE on the 84 XR350R dual carb

Took apart the bike tonight. Got it ready to pull the engine off the frame. Pulled the exhaust and carbs.

My buddy and I discovered why the motor is locked. I orginally thought this was going to be a problem at the starter shaft gear, ratchet, starter idler, or a sheared tooth. That wasnt the case. We found that 1 intake valve was cracked probably from contacting the piston and from looking at it externally through the intake port with a flashlight the intake valve was not returning to the valve seat so it looks stuck open which makes me think its bent.. I dont know the root cause yet.  We opened the valve cover for that valve and found that the rocker arm isnt even making contact with the valve like its loose.. 

This again tells me the intake valve is bent as far as we can tell at this point in our diagnosis. Cant say for sure. Its deffinitely cracked though at the base. So, we found what has locked her up. Havent root caused it yet. 

I plan on pulling the cylinder head off of the block to inspect the damage in the cylinder head and the piston. Should I be worried that the connecting rod is damaged too? Can the valve guides be replaced if they need to be? 

Im expecting to have to replace atleast 1 intake valve. Maybe the piston too.

Last question for tonight is who is a trustworthy source to buy intake valves from? Not ordering parts yet as the motor isnt apart but im going to start browsing. Should i be searching for genuine OEM Honda Valves? Or aftermarket?

Thanks for taking the time to read, ive never pulled a motorcycle engine before. Im going to have a lot of questions.. Bear with me. 

Have a goodnight folks!

Edited July 10, 2019 by BorgenRS92

[nobade]

You don't have to pull the engine to remove the head. You do want to check parts availability though, I sold my XR350 because of that. Most everything unique to the 350 has been discontinued by Honda. Hopefully you can find what you need and hope it's not a bent con rod since those are few and far between.
I really liked that bike but rebuilding that engine costs more than a decent used dirt bike so I had to give up on it.

[gt63]

your cam chain skipped a tooth on the cam sprocket putting it out of time, the piston to contact the valve. you will need a new cam chain and possibly tentioner.

[BorgenRS92]

23 minutes ago, gt63 said:

your cam chain skipped a tooth on the cam sprocket putting it out of time, the piston to contact the valve. you will need a new cam chain and possibly tentioner.

I actually haven't checked the timing of the motor yet. I think I'm going to do that later today. New cam chain means I need to seperate the case on the lower end doesnt it?

[gt63]

4 hours ago, BorgenRS92 said:

I actually haven't checked the timing of the motor yet. I think I'm going to do that later today. New cam chain means I need to seperate the case on the lower end doesnt it?

no you don't have to split the case just the right side cover, pull the head to inspect the piston and con rod, you will need at least an intake valve or 2 and some gaskets.

[BorgenRS92]

All 4 valves were contacting the piston. Previous owner put a wiseco piston in and may have not timed correctly? 

Going to buy 4 new valves and send the head out to a machine shop. 

Wiseco still sells a piston kit for this bike so ill probably buy a wiseco piston kit for it. We havent measured the diameter of the bore so i dont know what size piston to buy yet.

Really satisfied with what we found. It looks like it can be saved!

[BorgenRS92]

I need help findind 2 new intake valves and 2 new exhaust valves for the 84 XR350R. 

I live in Macomb Michigan does anyone know of a reputable machine shop close by I can give my cylinder head too for a valve job? My buddy suggested Millenium Technologies in Wisconsin. I would like to try and find something closer to Detroit if possible.

Now i just need to gather parts before i start putting it together. And get the head work done. I plan on honing the cylinder bore, it looks fine but since ill be throwing in a new piston its probably a good idea to get that nice cross hatch aye? 

Connecting rod looks just fine.

Here are some pictures. Below is the intake valve that looks like it bent the most out of the 2 of 4 valves we pulled off the head. IT LOOKS LIKE ALL THE VALVES WERENT SEATING. Valve seats looked like shit. The one pictured below was stuck open. But it appears that all 4 valves are actually bent. Some more minor than the others. Check the top of the piston out too.

Now the important part is what actually caused this. Obviously the valve timing had to be off for this to happen. Previous owner put a piston in this motor either he timed it wrong from the start or the cam chain jumped after he installed his piston. Is there a way to see if the cam chain is stretched out of tolerance? Its hard to believe that chain can stretch it looks pretty damn beefy. The cam chain tensioner appears to be okay too. But shouldnt i replace the tensioner and cam chain if i can find them for sale? Could this have happened because the chain lost too much tension? I dont want this to happen again haha

[Trailryder42]

The damage in the piston dome from the valves do not seem to match the original recesses meant to accept them, telling me that it's the wrong piston, or maybe it was installed backwards.

[gt63]

looks to me that the engine was running with that piston for a while due to the amount of carbon so I wouldn't think it was installed backwards,  check with Honda for the chain and valves, the last chain I bought was a DID in Honda oem packaging from Honda (83 xr350r), I think that was around 5 years ago, good luck. 

[BorgenRS92]

Is anyone familiar with the XR400 exhaust valves compared to the XR350 exhaust valve? 

 

 

or

What about XL350 valves in a XR350R? Can any of these valves be used in the XR head?

It looks like Kibblewhite could make these valves but I need all the dimensions of the valve to give them for a quote. I was beginnning to part the bike out due to part availability but my girlfriend of 3 years just broke up with me so I think I may put her back together.. Lol

[Zahnarzt]

11 hours ago, BorgenRS92 said:

Is anyone familiar with the XR400 exhaust valves compared to the XR350 exhaust valve? 

 

 

or

What about XL350 valves in a XR350R? Can any of these valves be used in the XR head?

It looks like Kibblewhite could make these valves but I need all the dimensions of the valve to give them for a quote. I was beginnning to part the bike out due to part availability but my girlfriend of 3 years just broke up with me so I think I may put her back together.. Lol

The XR350R exhaust valves can be had on RockyMountain or the like while the intakes can't...

Not sure about the XR400 valve, but the TRX400EX valves are the same """EXCEPT 1mm  shorter"

I am not connected enough with my XR350 to go the Kibblewhite route, so I am going to install the 400EX valves (which I have as spares) and just giv'er piss until it blows. I'll probably crash way before that so it's a win-win

[ThumperHead]

 

I haven't been lurking on these older XR & XL forums for several months. 

As Trailryder42  mentioned above, I fully agree the piston reliefs DO NOT look proper for the valve combination of your engine. I see the outer radius of the pocket contact marks made from the diameter of the valve as a contact area which would cause any engine failure long before the bottom of the valve reliefs making contact with the top of the valve head.  Install new valves, MOCK UP ONLY the engine (assemble for checking clearances only) with modeling clay filling up the valve relief pockets in the piston. Oil coat the clay preventing sticking to valves. Slowly carefully hand rotate the engine two plus crank rotations. STOP if you feel any solid mechanical lockup vs bending valves again, remove head then razor blade cut the clay looking for left behind clay thickness which would be your piston to valve safety clearance. This from bottom of relief pocket as well the relief wall to outer valve diameter clearance which already looking suspect. Aftermarket piston already suspect and best checking relief pocket diameters with a known original Honda piston. 

On valve dimensions I recall the same valve diameters and lengths used with XR's and XL's 350 engines as well the valve seats. You should check the guides for damage possibly now "bell mouthed" or split at the ports unless your got lucky and still within factory spec clearances to stems then only a little seat dressing required. 

Cam chain stretch would appear looking at the cam gear dash lines 180* apart near the teeth vs the top of the head surface, should be parallel with each other, this at TDC of the crank set first. Stretched chain plus worn sprockets will cause the cam to be retarded to the crank hence a little low end power loss causing power to be shifted slightly towards top end rpm's......~~=o&o>.......  

[gt63]

i'm rethinking the backward installed piston, lets say the piston was installed incorrectly (backwards) , now the cam chain goes out of time and the piston contacts the valves before TDC, I'm looking at the top of the piston pic and to me it looks like IF the piston was installed correctly those strike marks would be in the valve reliefs in the top of the piston instead of beside the reliefs, what do you all think.  

[Trailryder42]

5 hours ago, gt63 said:

i'm rethinking the backward installed piston, lets say the piston was installed incorrectly (backwards) , now the cam chain goes out of time and the piston contacts the valves before TDC, I'm looking at the top of the piston pic and to me it looks like IF the piston was installed correctly those strike marks would be in the valve reliefs in the top of the piston instead of beside the reliefs, what do you all think.  

That was my thinking when I suggested it above. It's either installed wrong or the wrong piston for the application.

[BorgenRS92]

18 hours ago, gt63 said:

i'm rethinking the backward installed piston, lets say the piston was installed incorrectly (backwards) , now the cam chain goes out of time and the piston contacts the valves before TDC, I'm looking at the top of the piston pic and to me it looks like IF the piston was installed correctly those strike marks would be in the valve reliefs in the top of the piston instead of beside the reliefs, what do you all think.  

I agree. That is what puzzles me. 

 

I should post a picture with the carbon cleaned off of the piston. I dont think the wrong piston was in there or that it was installed in the wrong orientation. The bike sits at my friends house so I cant just go out and work on whenever id like too. 

 

[BorgenRS92]

Found XL350 exhaust valves on ebay.

So from what ThumperHead is saying I can save this engine with these older XL350 exhaust valves? Is there a place I can prove thats the case? 
14721-356-000 NOS Honda Exhaust Valve XL350 1974-1978 K448c

 

 

 

[BorgenRS92]

https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.com%2Fulk%2Fitm%2F132782552289

[BorgenRS92]

Update: So I believe the piston was installed backwards. I found exhaust valves in Australia, found intake valves in the USA. So I have those ordered. I ordered a complete gasket kit. Ordered a new Wiseco piston set. I will give updates as the rebuild progresses. Thanks!