Project 3LN1 Restoration

Ok, so, @ruckusman , for some reason the keyster float needles won’t fit down the float seat hole, they just stop on a lip at the top, will investigate this further once I sort out a level surface for the bike to measure the fuel levels. I got my #100 Mikuni main jet so that’s all sorted. I have however encountered an issue regarding the jet needles. It seems all of them are 5CT7 needles and the clip is on the top position on all of them. Luckily, in the box of parts there seems to be 2 5CT9 needles however they have some wear on the tip of them, see pic:

As this is also my first time adjusting needle clip positions I’m assuming 3rd Notch means 3 down from the top however does this mean the brown plastic ring goes below the clip on the 3rd position or are we setting them so the brown plastic ring is sitting on the 3rd position, thanks heaps.
Example of what I currently assume 3rd position means.

 

Ok, I have installed the carbs, checked the fuel levels and they are all around 10.5mm so that’s good. The idle changes itself randomly however and there’s still some white smoke coming out of the exhaust when you shine a flashlight on it.( might be water leak on head gasket or something). Any checks I should do or something I should video for you guys to see, I let the engine come up to temperature and I revved it to 15k rpm as a quick test and it sounds ok. When releasing the throttle if the idle is set lower and was fine before revving, it can sometimes drop to 0 rpm and then cut out. Or, if I set it higher and it also seems ok, it will increase revs after letting off the throttle. As shown in video below:



The white smoke is in the video below:




Sent from my iPhone using Tapatalk

 

Ok cheers, I’ll turn them down half a turn and suss tomorrow. Is the white smoke ok? Also does the engine sound fine, I wouldn’t have the carbs this perfect if it wasn’t for you so I appreciate it heaps. Just worried of any other internal issues, piston rings, leaking head gasket, valve clearances. Don’t want to blow it up haha.

 

I initially thought it was condensation however it remained consistent even after the engine came up to temperature. Also, I might mention that on 1 rev there was some black smoke will attach video, only once though. The rest were just light white smoke. I’m going to finish rebuilding the brakes tomorrow and will sort out a roadworthy so I can test it out on the road soon. Will also need to change the tyres.

 

The hand brake bleeder also arrived and so did the master cylinder and lines you sent me, once again thanks for that.

 

Yep, 14.7mm results in a 10.5mm float height. I will need to draw a proper 10.5 mm mark on my fuel level measuring device and double check them all again just to make sure and change over to the keyster needles. I do also wonder however whether the float bowl pushes the float seat further down once installed and hence the actual float height is technically lower than 14.7, I guess this is largely irrelevant though if the fuel level is correct.

I agree, thanks to you and everyone on this forum the carbs are almost perfect and the bike is finally seeing proper fueling requirements for the first time in years. Now, with this knowledge, I can hope to help others on this forum get to the same point as I have learnt so much thanks to you guys.

Lets just hope it isn’t worn somewhere else and blows up on my first ride. I can already see a coolant leak I’ll need to fix. I don’t know how many years it has been since this bike has been ridden as the previous owner bought it with the ceased brakes, put the incorrectly set up 3LN3 carbs on, started the bike for the first time in ages, realised he didn’t have enough time and sold it to me.

If only I didn’t work full time and do full time uni at the same time, I would already have it all done by now. Not far to go though, any tire recommendations btw ahah.

 

This is exactly why I wanted one of these so badly, they are peak Japanese engineering and the inline 4 revving so balanced and high is so awesome especially with carbs. I really just want to restore the whole thing bit by bit so I can see how awesomely complex it is on the inside. The crazy thing to think about it is that the engine is tuned like a race bike but came with warranty from the factory as a race 250 for the road.

I have an r6 rear shock on the way in the mail so I’ll need to enquire with you guys about dog bone length changes soon.

Will get on valve clearances in the next few days, thanks for those tips, will take them into account. Hopefully I don’t ruin the rocker cover gasket but I’ll put some gasket glue.

On another note, I’m trying to source another 3LN1 right now for parts or a potential second project. I’m going to try test my skills and develop a good intake manifold for a fuel injected version of this thing if I have time. It would be interesting to see what can be done with an ecu and some small injectors.