PlanetMinis Forums banner
1 - 15 of 15 Posts

·
Registered
Joined
·
6 Posts
Discussion Starter · #1 ·
Hi, love the forum! I have a very nice, low-hour 86 TRX70 that has been kicking my butt. Starts and runs well, but boggs when given WOT. It will wind out if given throttle slowly, but seems to lack power.



Takes WOT on choke, which might indicate a clogged jet, but both jets have been replaced and carb cleaned multiple times, all passages clear. Also installed a carb rebuild kit, and swapped out carb bodies with another used one. No joy.



Exhaust smells rich, and plugs sometimes carbon-foul, but the fact that it takes WOT on choke should indicate a lean condition. I'm kinda confused and hoping someone else has conquered this problem on the Honda 70 and can help. Thanks a lot for any help.

-Paul
 

·
Registered
Joined
·
383 Posts
Paul C said:
Hi, love the forum! I have a very nice, low-hour 86 TRX70 that has been kicking my butt. Starts and runs well, but boggs when given WOT. It will wind out if given throttle slowly, but seems to lack power.



Takes WOT on choke, which might indicate a clogged jet, but both jets have been replaced and carb cleaned multiple times, all passages clear. Also installed a carb rebuild kit, and swapped out carb bodies with another used one. No joy.



Exhaust smells rich, and plugs sometimes carbon-foul, but the fact that it takes WOT on choke should indicate a lean condition. I'm kinda confused and hoping someone else has conquered this problem on the Honda 70 and can help. Thanks a lot for any help.

-Paul


Are you running the stock air cleaner with OEM style filter (freshly oiled)? Aftermarket / modified pipe?



How's your fuel flow to the carb? In tank filter is clean and free flowing?



Check for intake leaks (air), spray WD40 around the intake manifold and gaskets, if engine falls off or stutters start there.



Check for proper valve clearance (hard start, low power).



Once you get frustrated enough, I'll take it off your hands
 

·
Registered
Joined
·
6 Posts
Discussion Starter · #4 ·
Thanks....I've pondered the ignition myself lately. Yesterday I swapped the main het (#62) for a #65....bike ran horribly, and fouled a new C7HS within a minute. Went back to the #62 and blasted out all the carb passages once again, and the bike is back to the way it was. If it it hot (e.g: after blasting down the road wide open) it will take throttle from idle.

All the jets I have are larger....maybe I am going the wrong direction? Also, the spark appears weaker than I'm used to, which led me to suspect the CDI. On all my larger machines, there is usually a big, fat blue spark, not so much on this one. Thoughts?
 

·
Registered
Joined
·
383 Posts
Paul C said:
Thanks....I've pondered the ignition myself lately. Yesterday I swapped the main het (#62) for a #65....bike ran horribly, and fouled a new C7HS within a minute. Went back to the #62 and blasted out all the carb passages once again, and the bike is back to the way it was. If it it hot (e.g: after blasting down the road wide open) it will take throttle from idle.

All the jets I have are larger....maybe I am going the wrong direction? Also, the spark appears weaker than I'm used to, which led me to suspect the CDI. On all my larger machines, there is usually a big, fat blue spark, not so much on this one. Thoughts?


Your 22 year old spark plug wire and coil just might be an issue. Check / renew the coil's ground connection and replace the spark plug cap at least if you can't change the wire as well. Some are molded into the coil, others are serviceable (you will see a plastic nut where the wire enters the coil if it is serviceable). If it's molded, leave it alone.



You owe it to yourself to check valve clearances before doing anything else.
 

·
Registered
Joined
·
6 Posts
Discussion Starter · #7 ·
Thanks, I'll investigate the plug wire/cap and coil today. Timing and valve last is good, set .002.
 

·
Registered
Joined
·
6 Posts
Discussion Starter · #8 ·
Cleaned and replaced the chassis ground connector, snipped the end off the spark plug wire and reseated connection. No change at all in performance. Guess I'm still confused as ever:confused:
 

·
Registered
Joined
·
67 Posts
hello, I've been away from this site for some time . first, is it hard to start. do you have to pull like until your arm is numb? if your spark is weak like you say and it runs on the choke, here are my suggestions. check your cam timing and make sure when the piston is at top dead center the dot on the cam gear is aligned with the notch in the head. then since your there at top dead, check your gap between the pickup and the weight on the flywheel.(and clean) and then I would check with the needle height. see if its to high and making the carb jump to the main jet to soon. and then last I would check to see if the float level is wrong. and then open the gap up on your plug.



I have a trx70 that I would like to sell. I put a 90cc electric start engine in it. it has new plastic, tires, seat, tank, grips, my oldest has grown out of it and time for her to move on. If I don't, she may loose interest and want a horse....please help. reach me at [email protected] and I can get you some pics. thanks haxtoon
 

·
Registered
Joined
·
6 Posts
Discussion Starter · #10 ·
Hey, thanks a lot for the reply. The timing is good, but I have not had the entire flywheel cover off yet. I'll check that gap tomorrow. I have the carb needle on the center notch currently, but have set it all the way rich and all the way lean before, and the difference is negligible. I know it seems oddd, but the machine has good days andd bad, when it seems to run really well, then run like garbage the next day..strange.
 

·
Registered
Joined
·
214 Posts
My 86 TRX70 is doing the same exact thing. Starts with one pull, idles great, stumbles really bad in the mid range, runs great at full throttle. It won't even pull itself up my driveway. It wil run fine with the choke on though, so it points to being lean. I have the needle clip in the bottom position and it doesn't change, I even put a shim under the clip to raise it more but it didn't help. I even swapped the carb out from a good running ATC 70 and as Paul C says "no joy". I did take the flywheel off and the stator plate was pretty grimy. So I am going to de-grease it today and see what happens. I hope this fixes it, I have checked all the obvious things and am getting frustrated.
 

·
Registered
Joined
·
656 Posts
any luck with your problem?is your float height correct?what about tank venting,or the in tank petcock filters?
 

·
Registered
Joined
·
214 Posts
I replaced the stator plate on mine and no change. Mine runs fine when in nuetral, smooth all the way through the rpm range. While in gear though it bogs and won't pull at all.
 

·
Registered
Joined
·
6 Posts
Discussion Starter · #15 ·
Hey guys, sorry its been so long since I posted on this, I lost interest for a little while. Last week I pulled the TRX out and installed a brand new carb (aftermarket to stock spec) I got from ebay. The bike pretty much runs the same. In an effort to troubleshoot I did the following:

-New plug: C7HSA

-Swapped coil with known good

In the process of re-installing the old coil, I stood the machine up on the rear bar. When I lowered it back down, it ran better. It would actually take WOT from idle and run well. I thought maybe some fuel had leaked backward from the carb and soaked the filter, creating more back pressure. I removed and re-oiled the filter, it ran slightly better. After it got hot, it ran OK, and the kids played on it for a while.

**After sitting 3 days, the machine was very hard to start (several pulls) and was very cold natured once I got it running. I wanted to test compression, but don't have a small enough adapter. Soo...I stood it up on end and re-torqued the acorn nuts on the head in case it is possibly leaking from the head or base gaskets. Set it down, ran really well. Now I am letting it cool off and I will try later and see what I've got.

Sorry for the long read, and thanks for any advice, I can't believe a Honda 70 is beating me up...still.

-Paul
 
1 - 15 of 15 Posts
Top