Honds sl90 no start
So I have a 1969 sl90 i bought for a good deal, I know not ct 90 but same engine so I thought you guys might be able to help. I did a top end refresh and am getting about 100 psi compression cold I know that is low im hoping it just needs to run in with the…
So I have a 1969 sl90 i bought for a good deal, I know not ct 90 but same engine so I thought you guys might be able to help. I did a top end refresh and am getting about 100 psi compression cold I know that is low im hoping it just needs to run in with the new rings or else ill have to get the valves done or a new head gasket possibly. So I have compression or at least enough in my mind to pop over( I have the carb off and am attempting to get it to pop by squirting starter fluid into the intake). I have set the valves and the points gap and the ignition timing statically ( new points from common motor) so I dont believe any of those things are my isue, I get strong looking blue spark with the spark plug outside of the engine when the condensor is bypassed but not with the condensor installed ( brand new condensor from common motor that i tested with a multimeter and i believe is is good working order ) wich is a problem I've never run into on my other projects. Im wondering if it's a bad coil the coil i have on there came with the bike and appears not to be original because it does not align with both holes on the mounting bracket. Im stumped as to what my next move here should be. Another note is when installing the cylinder onto the crank case I had to make an extra thick base gasket because the bottom of the cylinder sleeve was making contact with I believe the crank and not alowing the engine to turn over when the head was fully torqued down. It turns freely now with the thick gasket I made so I dont believe this is related to my no start problem but I figured I'd throw it in for good measure. TlDR I have a non running honda sl90 with 100 psi compression after new piston and cylinder and I have to bypass the new condensor to get spark when testing outside the engine
Collected discussion
Moderator Announcement Read More » Thanks for posting on r/MechanicAdvice! Please review the rules. Remember to please post the year/make/model of the vehicle you are working on. Post's about bodywork, accident damage, paint, dent/ding, questions it belongs in r/Autobody r/AutoBodyRepair/ or r/Diyautobody/ Tire questions check out https://www.reddit.com/r/MechanicAdvice/comments/k9ll55/can_your_tire_be_repaired/. If you dont have a question and you're just showing off it belongs in r/Justrolledintotheshop Insurance/total loss questions go in r/insurance This is an automated reply I am a bot, and this action was performed automatically. Please contact the moderators of this subreddit if you have any questions or concerns.
Probably Going to take the head and possibly cylinger block to the machine shop tomorrow( kicking myself now for not putting my milling machine together now ) but I checked the original cylinder against the one I got wich appears to be an oem honda cylinder note it did come from Thailand if that is relevant and they appear the same
"I did a refresh" This is how a concerning increasing number of posts in this sub are starting these days. 100psi work out to around 690kPa: the lower limit for these 90cc Honda engines is 980kPa (around 140psi) and these engines came from the factory at 1170 kPa (around 170 psi). In short that engine has extremely low compression. Post a picture of that cylinder block: I suspect you got a "Frakenengine" with one of those sketchy made in Taiwan cylinder blocks that were once so common. Also pictures of the cylinder/crankcase mating surface would be welcome.