Hi guys, I’m in a pickle, would appreciate anyones help. Basically, I’m trying to connect up all the liquid cooled hoses, oil hoses etc and I’m slightly confused. I’ve managed to connect the main four hoses to and from the coolant reservoir to the radiator which has left me with two main large hoses which come from the bottom of the radiator, one goes directly into the head and the other goes into the engine via the stator side inlet pipe. Now here is where I’m a bit puzzled, on the main inlet coolant pipe (stator side) on the same inlet pipe there is a T’d smaller nipple inlet, which is pretty much the same size as the other small inlet nipple which is on the head of the malossi 70 lc sports kit. I don’t know what to plug in where or what, with these two smaller nipples, I’m also a bit unsure of the carb feeds, ive got a 17.5 dellorto standard carb, it has a coolant in, coolant out, oil in and petrol in nipples, I’m assuming that the nipples on the head and the stator inlet, connect to the carbs coolant in/out somehow? If anyone knows how to properly connect this up, I’d be forever grateful, I don’t want to mess things up as I’ve completely stripped the bike and rebuilt the engine with new crank, gears etc and would hate to mess this part up! Will attach some pictures. ibb.co/GPd9CYx ibb.co/vc1YJZx ibb.co/j42wjQZ
Small pipe off cylinder head to union on carb, out carb to bottom hose under flywheel.[ water unions are close together] this is the thermostat bypass for when engine is cold and stat is closed, water must have a path to flow. Oil into carb is obviuosly the tiny union.
You’re a diamond, thank you so much. What is the cylinder head nipple and which union does that go into on the carb exactly? Sorry I’m just trying to learn what these things are so I know it’s workings.. So hose from cylinder to carb (which nipple?) then back out the carb to the small nipple near the flywheel, oil tank has a main feed from the bottom of the oil tank that goes to the oil pump right? Then a smaller oil pipe that goes into the carb inlet? Is that right? What goes into the union/nipple which is near the reed valve on the actual engine? Is that a vacuum or fuel? I’m thinking it’s vacuum? Because shouldn’t fuel be fed into the carb? Thanks again, I’m trying to learn the mechanics of this, so I remember what goes where!
Another quick question, where does the vacuum hose fit on the carb from the mini petrol reservoir? It has two unions, one lower and one above, from what I’ve found, the lower is supposed to fit to a vacuum of some sort and the upper is the main feed for the fuel to the carb? The vid I found shows to put the lower hose into the carbs vacuum union but my carb doesn’t seem to have one, I’ve got a dellorto 17.5mm phva id carb, it has four unions, 2x coolant in/out, 1 oil and one for fuel, so I’m baffled. edit: I’ve found a T splitter from when I stripped the bike, could this have been used for the fuel vacuum line? So, combining the vacuum from the pump that goes to the reed valve union, with the vacuum line that is needed for the small fuel reservoirs ‘auto petcock’ if that makes sense? Because I have no vacuum union on the carb, just thinking if I can steal the same vacuum from the pump that goes into the reed union…?
The two water unions are close to each other, petrol in is on it's own on the front side of carb. The union just below reed block is vacuum { positive/negative pressure} to the petrol pump. The oil in union is brass.
thank you, I was confused though, as my carb doesn’t have a vacuum union that should lead to the mini petrol tanks ‘vacuum’ pet cock lower union, so I’m assuming I must use a T to connect the petrol cocks vacuum union, with the same line as the pumps vacuum output and have both these connecting to the reed block vacuum? Is that right?
Does anyone have any ideas on this? no vacuum union on my 17.5mm dellorto carb (stock) that should plug into the vacuum union of the small petrol tank. I could just get a T as mentioned above and share the reed block vacuum with the petrol pumps vacuum but when I took the bike apart, I didn’t see a T there before, so I’m baffled as to how it worked before, before changing. anyone have any experience with this bike?
The small petrol header tank has a vacuum union on the carb, petrol pump under petrol tank is taken off the engine case just under reed block.
@MARSH i totally get that, and that’s how I’ve seen it done on a video too, but my carb doesn’t have a vacuum union and this is where I’m getting confused, there’s no vacuum on my dellorto 17.5mm carb. So I’m baffled as to where to get vacuum for the small petrol header tank pet cock from?? this seems to be the carb I’ve got… as it’s spec, it doesn’t have a vacuum union, only water heating connections and oil feed - https://www.dellorto.co.uk/shop/del...s-parts/phva-12-to-17-5mm/r8448-phva-17-5-id/ Any ideas? This is where my entire confusion comes from, I know I’ve been told to just get a plastic T and use this to plug both the pumps vacuum line as well as the petrol header tanks vacuum line and then a single line directly into the engines reed vacuum but then I’ve heard mixed opinions on this.
The petrol pump under the main tank needs a positive/negative pressure to work, that's why it's taken of engine case under reed block. Small header tank needs a negative vacuum to open it, if you have a std carb it should have the vacuum union if not then fit one.
@MARSH So it won’t run if I tie the block vacuum with the pet cock then? also, quick question, is the vacuum union supposed to be installed on the inlet side where the carb joins to the red valve? Any documentation on doing this at all? I know it sounds stupid, a guide on how to insert a union into a hole, but I don’t want to mess anything up. what also baffles me is the carb came with the bike, I haven’t changed it, there was no vac union on it but it ran? Weird
Any reasons why? I’d rather pay for a union that have to buy an expensive part… do you recommend an alternative for a 70cc that will bolt straight onto the current manifold?
